🏆 Time Signal Simple Present Continuous Tense

Discrete-Time Signal ProcessingW. Kenneth Jenkins, ... Bill J. Hunsinger, in Reference Data for Engineers Ninth Edition, 2002Basic DefinitionsA continuous-time CT signal is a function, st, that is defined for all time t contained in some interval on the real line. For historical reasons, CT signals are often called analog signals. If the domain of definition for st is restricted to a set of discrete points tn = nT, where n is an integer and T is the sampling period, the signal stn is called a discrete-time DT signal. Often, if the sampling interval is well understood within the context of the discussion, the sampling period is normalized by T = 1, and a DT signal is represented simply as a sequence sn. If the values of the sequence sn are to be represented with a finite number of bits as required in a finite state machine, then sn can take on only a discrete set of values. In this case, sn is called a digital signal. Much of the theory that is used in DSP is actually the theory of DT signals and DT systems, in that no amplitude quantization is assumed in the mathematics. However, all signals processed in binary machines are truly digital signals. One important question that arises in virtually every application is the question of how many bits are required in the representation of the digital signals to guarantee that the performance of the digital system is acceptably close to the performance of the ideal DT CT systems are characterized by the familiar mathematics of differential equations, continuous convolution operators, Laplace transforms, and Fourier transforms. Similarly, linear DT systems are described by the mathematics of difference equations, discrete convolution operators, Z-transforms, and discrete Fourier transforms. It appears that for every major concept in CT systems, there is a similar concept for DT systems differential equations and difference equations, continuous convolution and discrete convolution, etc.. However, in spite of this duality of concepts, it is impossible to apply directly the mathematics of CT systems to DT systems, or vice modern systems consist of both analog and digital subsystems, with appropriate analog-to-digital A/D and digital-to-analog D/A devices at the interfaces. For example, it is common to use a digital computer in the control loop of an analog plant. Analytical difficulties often occur at the boundaries between the analog and digital portions of the system because the mathematics used on the two sides of the interface must be different. It is often useful to assume that a sequence sn is derived from an analog signal sat by ideal sampling, 1sn=satt=nTAn alternative model for the sampled signal is denoted by s*t and defined byEq. 2s*t=∑n=−∞+∞satδat−nTwhere δat is an analog impulse function. Both sn and s*t are used throughout the literature to represent an ideal sampled signal. Note that even though sn and s*t represent the same essential information, sn is a DT signal and s*t is a CT signal. Hence, they are not mathematically identical. In fact, sn is a “DT-world” model of a sampled signal, whereas s*t is a “CT-world” model of the same full chapterURL Analysis of Discrete-time Signals and SystemsLuis Chaparro, in Signals and Systems Using MATLAB Second Edition, Energy/Power of Aperiodic Discrete-time SignalsAs for continuous-time signals, the energy or power of a discrete-time signal x[n] can be equivalently computed in time or in Energy Equivalence—If the DTFT of a finite-energy signal x[n] is Xej, the energy Ex of the signal is given by Power Equivalence—The power of a finite-power signal y[n] is given by windowThe Parseval’s energy equivalence for finite-energy x[n] is obtained as followsEx=∑nx[n]2=∑nx[n]x∗[n]=∑nx[n]12π∫-ππX∗eje-jnd=12π∫-ππX∗ej∑nx[n]e-jn︸Xejd=12π∫-ππXej magnitude square Xej2 has the units of energy per radian, and so it is called an energy density. When Xej2 is plotted against frequency , the plot is called the energy spectrum of the signal, or how the energy of the signal is distributed over if the signal y[n] has finite power we have thatPy=limN→∞12N+1∑n=-NNy[n]2and windowing y[n] with a rectangular window W2N+1[n]yN[n]=y[n]W2N+1[n]whereW2N+1[n]=1-N≤n≤N0otherwisewe have thatPy=limN→∞12N+1∑n=-∞∞yN[n]2=limN→∞12N+112π∫-ππYNej2d=12π∫-ππlimN→∞YNej22N+1︸SyejdPlotting Syej as a function of provides the distribution of the power over frequency. Periodic signals constitute a special case of finite-power signals and their power spectrum is much simplified by their Fourier series as we will see later in this significance of the above results is that for any signal, whether finite energy or finite power, we obtain a way to determine how the energy or power of the signal is distributed over frequency. The plots of Xej2 and Syej versus , corresponding to the finite-energy signal x[n] and the finite-power signal y[n] are called the energy spectrum and the power spectrum, respectively. If the signal is known to be infinite energy and finite power, the windowed computation of the power allows us to approximate the power and the power spectrum for a finite number of full chapterURL Fourier AnalysisLuis F. Chaparro, Aydin Akan, in Signals and Systems Using MATLAB Third Edition, Energy/Power of Aperiodic Discrete-Time SignalsAs for continuous-time signals, the energy or power of a discrete-time signal x[n] can be equivalently computed in time or in energy equivalence—If the DTFT of a finite-energy signal x[n] is Xej, the energy Ex of the signal is given by Parseval's power equivalence—The power of a finite-power signal y[n] is given by of yN[n],W2N+1=u[n+N]−u[n−N+1]rectangular Parseval's energy equivalence for finite energy x[n] is obtained as followsEx=∑nx[n]2=∑nx[n]x⁎[n]=∑nx[n][12π∫−ππX⁎eje−jnd]=12π∫−ππX⁎ej∑nx[n]e−jn︸Xejd=12π∫−ππXej2d. The magnitude square Xej2 has the units of energy per radian, and so it is called an energy density. When Xej2 is plotted against frequency , the plot is called the energy spectrum of the signal, or how the energy of the signal is distributed over if the signal y[n] has finite power we havePy=limN→∞⁡12N+1∑n=−NNy[n]2 and windowing y[n] with a rectangular window W2N+1[n]yN[n]=y[n]W2N+1[n]whereW2N+1[n]={1−N≤n≤N,0otherwise, we havePy=limN→∞⁡12N+1∑n=−∞∞yN[n]2=limN→∞⁡12N+1[12π∫−ππYNej2d]=12π∫−ππlimN→∞⁡YNej22N+1︸Syejd. Plotting Syej as a function of provides the distribution of the power over frequency. Periodic signals constitute a special case of finite-power signals and their power spectrum is much simplified by their Fourier series as we will see later in this significance of the above results is that for any signal, whether of finite energy or of finite power, we obtain a way to determine how the energy or power of the signal is distributed over frequency. The plots of Xej2 and Syej versus , corresponding to the finite-energy signal x[n] and the finite-power signal y[n] are called the energy spectrum and the power spectrum, respectively. If the signal is known to be infinite energy and finite power, the windowed computation of the power allows us to approximate the power and the power spectrum for a finite number of full chapterURL Ling, in Nonlinear Digital Filters, 2007Relationships among continuous time signals, sampled signals and discrete time signals in the frequency domainDenote a continuous time signal as xt and sampling frequency as fs. Then the sampling period is 1fs and the continuous time sampled signal is xst=xt∑δt−nfs. By taking the continuous time Fourier transform on this sampled signal, we have Xs=fs∑∀nX−2πfsn.. Since Xs is periodic with period 2πfs, if X is bandlimited within –πfs, πfs, then X can be reconstructed via a simple lowpass filtering with passband of the filter –πfs, πfs. Hence, if a signal is bandlimited by –πfs, πfs, fs is the minimum sampling frequency that can guarantee perfect frequency is called the Nyquist frequency. As xt ∑∀nδ t−nfs=∑∀nx nfs δ t−nfs, by taking continuous time Fourier transform on both sides, we have fs∑∀nX −2πfsn=∑∀nx nfse−jnfs. Denote a discrete time sequence as xnfs, taking the discrete time Fourier transform on this discrete time sequence, we have XD=∑∀nxnfs e−jn. Hence, we have XDfs=Xs=fs∑∀nX−2πfsn.Read full chapterURL to Digital Signal ProcessingWinser Alexander, Cranos Williams, in Digital Signal Processing, IntroductionAdvances in digital circuit and systems technology have had a dramatic impact on modern society related to the use of computer technology for many applications that affect our daily lives. These advances have enabled corresponding advances in digital signal processing DSP which have led to the use of DSP for many applications such as digital noise filtering, frequency analysis of signals, speech recognition and compression, noise cancellation and analysis of biomedical signals, image enhancement, and many other applications related to communications, television, data storage and retrieval, information processing, etc. [1].A signal can be considered to be something that conveys information [2]. For example, a signal can convey information about the state or behavior of a physical system or a physical phenomena, or it can be used to transmit information across a communication media. Signals can be used for the purpose of communicating information between humans, between humans and machines, or between two or more machines. The information in a signal is represented as variations in the patterns for some quantity that can be manipulated, stored, or transmitted by a physical process [3]. For example, a speech signal can be represented as a function of time, and an image can be represented as a function of two spatial variables. The speech signal can be considered to be a one-dimensional signal because it has one independent variable, which is time. The image can be considered to be a two-dimensional signal because it has two independent variables such as width and height. It is common to use the convention of expressing the independent variable for one-dimensional signals as time, although the actual independent variable may not be time. This convention will generally be used in this independent variables for a signal may be continuous or discrete. A signal is considered to be a continuous time signal if it is defined over a continuum of the independent variable. A signal is considered to be discrete time if the independent variable only has discrete values. The values of a discrete time signal are often quantized, for many practical applications, to obtain numbers that can be represented for use in a digital circuit or system. A quantized, discrete time, signal is considered to be a digital signal. Thus, if both the independent and dependent variables are only defined at discrete values, then the signal is considered to be a digital signal. Digital signals can be represented as a sequence of finite precision play an important role in many activities in our daily lives. Signals such as speech, music, video, etc., are routinely encountered. A signal is a function of an independent variable such as time, distance, position, temperature, and pressure. For example, the speech and music we hear are signals represented by the air pressure at a point in space as a function of time. The ear converts the signal into a form that the brain can interpret. The video signal in a television consist of a sequence of images called frames and each frame can be considered to be an image. The video signal is a function of three variables two spatial coordinates and independent variables such as time, distance, temperature, etc., for many of the signals we interact with daily, can be considered to be continuous. Signals with continuous independent variables are considered to be continuous time signals. Advances in computer and digital systems technology have made it practical to sample and quantize many of these signals and process them using digital circuits and systems for practical applications. The processing of signals using computers and other digital systems is called digital signal processing. Digital signal processing involves the sampling, quantization and processing of these signals for many applications including communications, voice processing, image processing, digital communications, the transfer of data over the internet, and various kinds of data applications that involve continuous time signals are implemented using digital signal processing. The continuous time signals are quantized and coded in digital format to be processed by digital circuits and systems. The output from these digital systems is then either stored for later use of converted to continuous time signals to meet the requirements of the application. There are many reasons why digital signal processing has become a cost effective approach to implement many applications including speech processing, video processing and transmission, transmission of signals over communications media, and data retrieval and storage. Some of these reasons follow [4] programmable digital system provides the flexibility to configure a system for different applications. The processing algorithm can be modified by changing the system parameters or by changing the order of the operations through the use of software. Reconfiguring a continuous time system often means redesigning the system and changing or modifying its in continuous time or analog system components make it difficult for a designer to control the accuracy of the output signal. On the other hand, the accuracy of the output signal for a digital system is predictable and controllable by the type of arithmetic used and the number of bits used in the signals can be stored in digital computers, on disks or other storage media, without the loss of fidelity beyond that introduced by acquiring the signal through some process such as converting a continuous time signal to a digital signal. Storage media for continuous time signals are prone to the loss of signal accuracy over time and/or to the addition of noise due to implementation permits the easy sharing of a given processor among a number of signals by timesharing. Several digital signals can be combined, as one, using multiplexing. The multiplexed signal can then be processed by a single processor as needed for a particular application. The corresponding individual outputs can then be separated from the output of the digital system with the results being the same as if the signals were processed by different systems. This permits the use of a single high speed digital system to process several different digital signals with relatively low sampling signal processing can be used to easily process very low frequency signals such as seismic signals. Continuous time processing of these signals would require very large components such as large capacitors and/or large implementation cost of digital systems is often very low due to the manufacture of a large number of microprocessors or microchips with a single design. This has made it very cost effective to implement digital systems that can take advantage of being manufactured in large can be used to provide security with digital signals. This is important for internet security as well as security for wireless communications and the protection of personal are some disadvantages associated with digital signal processing digital signal processing system, for a particular application, is often more complicated than a corresponding analog signal processing upper frequency that can be represented for digital systems is determined by the sampling frequency. Thus, continuous time systems are still used for many high frequency systems use active circuits that consume power. Analog systems can be designed that use passive circuits which can result is the design of a system that consumes less power than a corresponding digital time signal processing is used in many applications considered to be in the category of information technology. Information technology includes such diverse subjects as speech processing, image processing, multimedia applications, computational engineering, visualization of data, database management, teleconferencing, remote operation of robots, autonomous vehicles, computer networks, simulation and modeling of physical systems, etc. Information technology, which is largely based upon the use of digital signal processing concepts, is essential for solving critical national problems in areas such as fundamental science and engineering, environment, health care, and government full chapterURL TheoryLuis F. Chaparro, Aydin Akan, in Signals and Systems Using MATLAB Third Edition, Sampling, Quantizing and Coding With MATLABThe conversion of a continuous-time signal into a digital signal consists of three steps sampling, quantizing and coding. These are the three operations an A/D converter does. To illustrate them consider a sinusoid xt=4cos⁡2πt. Its sampling period, according to the Nyquist sampling rate condition, isTs≤π/max= as the maximum frequency of xt is max=2π. We let Ts= s/sample to obtain a sampled signal xsnTs=4cos⁡2πnTs=4cos⁡2πn/100, a discrete sinusoid of period 100. The following script is used to get the sampled x[n] and the quantized xq[n] signals and the quantization error ε[n] see Fig. A period of sinusoid xt=4cos⁡2πt left-top, sampled sinusoid using Ts = right-top, quantized sinusoid using 4 levels left-bottom, quantization error right-bottom 0 ≤ ε ≤ Δ = 2. The quantization of the sampled signal is implemented with our function quantizer, which compares each of the samples xsnTs with 4 levels and assigns to each the corresponding level. Notice the approximation of the values given by the quantized signal to the actual values of the signal. The difference between the original and the quantized signal, or the quantization error, εnTs, is also computed and shown in Fig. The binary signal corresponding to the quantized signal is computed using our function coder which assigns the binary codes '10', '11', '00' and '01' to the 4 possible levels of the quantizer. The result is a sequence of 0s and 1s, each pair of digits sequentially corresponding to each of the samples of the quantized signal. The following is the function used to effect this full chapterURL TheoryLuis Chaparro, in Signals and Systems Using MATLAB Second Edition, Sampling, Quantizing, and Coding with MATLABThe conversion of a continuous-time signal into a digital signal consists of three steps sampling, quantizing, and coding. These are the three operations an A/D converter does. To illustrate them consider a sinusoid xt=4cos2πt. Its sampling period, according to the Nyquist sampling rate condition, isTs≤π/max= the maximum frequency of xt is max=2π. We let Ts = sec/sample to obtain a sampled signal xsnTs=4cos2πnTs=4cos2πn/100, a discrete sinusoid of period 100. The following script is used to get the sampled x[n] and the quantized xq[n] signals and the quantization error ε[n] see Figure A period of sinusoid xt=4cos2πt left-top, sampled sinusoid using Ts = right-top, quantized sinusoid using 4 levels left-bottom, quantization error right-bottom 0≤ε≤Δ=2.%%% Sampling, quantization and coding%%clear all; clf% continuous-time signalt=0 x=4*sin2*pi*t;% sampled signalTs= N=lengtht; n=0N−1;xs=4*sin2*pi*n*Ts;% quantized signalQ=2; % quantization levels is 2Q[d,y,e]=quantizerx,Q;% binary signalz=codery,dThe quantization of the sampled signal is implemented with our function quantizer which compares each of the samples xsnTs with four levels and assigns to each the corresponding level. Notice the approximation of the values given by the quantized signal to the actual values of the signal. The difference between the original and the quantized signal, or the quantization error, εnTs, is also computed and shown in Figure [d,y,e]=quantizerx,Q% Input x, signal to be quantized at 2Q levels% Outputs y, quantized signal% e, quantization error% USE [y,e]=midriserx,Q%N=lengthx; d=maxabsx/Q;for k=1N, if xk>=0, yk=floorxk/d*d; else if xk==minx, yk=xk/absxk*floorabsxk/d*d; else yk=xk/absxk*floorabsxk/d*d+d; end end if yk==2*d, yk=d; endende=x−yThe binary signal corresponding to the quantized signal is computed using our function coder which assigns the binary codes ’10’,’11’,’00’, and ’01’ to the 4 possible levels of the quantizer. The result is a sequence of 0s and 1s, each pair of digits sequentially corresponding to each of the samples of the quantized signal. The following is the function used to effect this z1=codery,delta% Coder for 4-level quantizer% input y quantized signal% output z1 binary sequence% USE z1=codery%z1=’00’; % starting codeN=lengthy;for n=1N, yn if yn== delta z=’01’; elseif yn==0 z=’00’; elseif yn== −delta z=’11’; else z=’10’; end z1=[z1 z];endM=lengthz1;z1=z13M % get rid of starting codeRead full chapterURL Signals and SystemsLuis F. Chaparro, Aydin Akan, in Signals and Systems Using MATLAB Third Edition, 2019AbstractThe theory of discrete- and continuous-time signals and systems is similar, but there are significant differences. As functions of an integer variable, discrete-time signals are naturally discrete or obtained from analog signals by sampling. Periodicity coincides for both types of signals, but integer periods in discrete-time periodic signals impose new restrictions. Energy, power, and symmetry of continuous-time signals are conceptually the same as for discrete-time signals. Basic signals just like those for continuous-time signals are defined without mathematical complications. Extending linearity and time invariance to discrete-time systems, a convolution sum represent them. Significant differences with continuous-time systems is that the solution of difference equations can be recursively obtained, and that the convolution sum provides a class of non-recursive systems not present in the analog domain. Causality and BIBO stability are conceptually the same for both types of systems. Basic theory of two-dimensional signals and systems are introduced. The theory of one-dimensional signals and systems are easily extended to two dimensions, however, many of the one-dimensional properties are not valid in two dimensions. Simulations using MATLAB clarify the theoretical full chapterURL of continuous and discrete time signalsAlvar M. Kabe, Brian H. Sako, in Structural Dynamics Fundamentals and Advanced Applications, AliasingIn the conversion of a continuous time signal to digital form, aliasing is a critical consideration. If aliasing occurs, then the sampled time signal will not be representative of the actual physical phenomenon. To prevent aliasing we must either sample at least twice the highest frequency contained in the analog data, or we must remove the spectral content above the Nyquist frequency one-half of the sampling rate before sampling. This removal is accomplished by filtering, which we will be discussed in Section However, for now it should be noted that in practice, because of limitations in filtering analog time histories, the sampling rate should be more than twice the Nyquist frequency. Accordingly, many data acquistion systems will ensure that the sampling rate is at least times the Nyquist is worth noting that we can compute the apparent frequency that waveforms above the Nyquist frequency will “fold back to” when sampled. Consider a sinusoid, xt=cos t, where =2πf. Suppose we sample xt at a sampling rate s=2πfs, where fs=1/Ts. Furthermore, assume that the sampling rate is inadequate to prevent aliasing, fs<2f. Let f0≤fs/2 and m is an integer. Then under sampling xt will produce an aliased signal with frequency equal to f0 Fig. we showed how a 1 Hz sinusoid f=1, when sampled with a period of sec fs=1/ resulted in a sampled signal that appeared to possess a period of 4 sec. Substituting into Eq. with m=1, we obtain f0= which corresponds to a period of 4 sec. Note that an infinite number of higher frequency waveforms could have folded back to yield the Hz sampled signal. Indeed, if we only know that the Hz waveform is an aliased signal, then for each combination of m and ±f0 there would be many possible higher frequency waveforms that could be the sources of the aliased shows an aliasing folding diagram. This tool is useful in determining how a signal with frequency higher than the Nyquist frequency fNyquist=fs/2 would fold to a lower frequency, f0, waveform. For example, suppose we sample a time signal at fs=1000 samples per second Hz, then fNyquist=1000/2=500 Hz. Now, suppose that the analog time signal contains waveforms with frequencies of f1=600 Hz, f2=1100 Hz, and f3=1700 Hz. Since each of these is above the Nyquist frequency, they will be aliased and appear in the sampled time signal as lower frequency waveforms at 400 Hz, 100 Hz, and 300 Hz, respectively see Eq. If the analog signal contained energy at any of these lower frequencies, the resulting sampled time signals will be the superposition of the actual low frequency content and the aliased waveforms. Note that the aliased waveforms can add constructively or destructively so that the sampled signal will appear to have greater or lower amplitudes, respectively, than in the analog Aliasing folding diagram for fNyquist=fs/2=500 Hz, f1=600 Hz, f2=1100 Hz, and f3=1700 arrows in the aliasing folding diagram also indicate the apparent frequency rate of change. For example, consider a sinusoid with increasing frequency, f, that would be used during a swept-sine test. Suppose that our sampling rate is not adequate and imagine that we are visually monitoring the sampled sinusoidal input. As f increases to fNyquist, the observed input will display an increasing frequency. As f passes fNyquist, the observed frequency, f0, will for a brief moment appear stationary and then begin to decrease. The decrease in f0 will continue until f approaches the sampling rate where it again appears stationary. Once f passes fs, the observed frequency will again increase. This apparent increase and decrease in the observed frequencies as f increases past multiples of fNyquist and fs explains the changing rotation rates of a tire as a car speeds up in a video taken with a slower constant frame full chapterURL Systems, and Spectral AnalysisAli Grami, in Introduction to Digital Communications, Continuous-Time and Discrete-Time SignalsA signal is said to be a continuous-time signal if it is defined for all time t, a real number. Continuous-time signals arise naturally when a physical signal, such as a light wave, is converted by a transducer, such as a photoelectric cell, into an electrical signal. A continuous-time signal can have zero value at certain instants of time or for some intervals of signal is said to be a discrete-time signal if it is defined only at discrete instants of time n. In other words, the independent variable on the horizontal axis has discrete values only it takes its value in the set of integers. Note that it does not mean a discrete-time signal has zero value at nondiscrete noninteger instants of time, it simply implies we do not have or probably we do not care to have the values at noninteger instants of time. A discrete-time signal gn is often derived from a continuous-time signal gt by the sampling process. Figure shows continuous-time and discrete-time full chapterURL

Weuse the present simple tense when we want to talk about fixed habits or routines - things that don't change. We use the present continuous to talk about actions which are happening at the present moment, but will soon finish. Compare these two statements: (present simple) I play tennis. (present continuous/ progressive) I am playing tennis.

Difference of the simple and continuous form of the presentWhat are the differences between the present simple and present continuous?Both the present simple and the present continuous are ways to express the present in English grammar. Although some other languages do make the distinction between simple and continuous forms too, others may not. In that case of no differentiation, learners of English may find the following explanation useful to understand this crucial point of the English tense system. It is usually not possible to exchange one form with the other one without changing the meaning. In detailComparison with peculiaritiesPresent simplePresent continuous/progressiveVerb in the base form infinitive read, see, wantAttention An s’ is added at the end of the verb if he, she, it’ is required reads, sees, wantsModal verbs never change their form may, will, might, shoulddo/does’ is needed in most questions and negative sentencesA present form of to be’ am, is, are is combined with the main verb which always ends in -ing’ reading, eating, …Merely not’ is required for negative sentences“They are not eating.”In most cases, it is employed for general statements that are no processes“The world is round.”or“Apples taste good.”Frequently used with verbs that express states smell, taste, like’, etc.Rare use of the ing-form for characteristics that are only valid temporarily, for example“He’s being very selfish today.”For regular actions like hobbies, for example“Martha reads a lot.”or“Nick plays baseball every Friday.”For processes and actions that are currently ongoing“Martha is reading her favourite book now.”or“Nick is playing baseball at the moment.”Scheduled events time tables are also typical for the present simple“The train leaves at 615.”For fixed appointments or arrangements in the future that have been made“We are leaving this evening.”What are the signal words for both tenses?If you are a learner of English with a native language that does not make a difference between these two aspects simple or continuous, it can be tough to differentiate. However, there are some certain expressions signal words that may help to use the forms properly – although the type of verb stative or action still needs to be considered too. Basically, you always have to determine if the statement refers to the current point in time or if it is more of general nature. CompareSignal words for the present simple and continuousPresent simplePresent continuousgenerally true or happening regularlyhappening at the moment or temporarilyExamplesoftennormallyusuallyalwaysneveroccasionallyExamplesnowat the momentLook!this weektoday

Introduction When the verb in a sentence refers to present time, without mentioning anything about the completeness or incompleteness of an action, it is in the present tense. Simple present tense is used to depict actions. taking place at the time of speaking. taking place for a finite period of time (show completion)

Home Grammar Verbs Simple Present Simple Present vs Present Continuous Two verb forms that are confusing for many students are the simple present and the present continuous also called the present progressive. Both of these verb forms talk about the current moment, now, the present—that’s why they are both in the present tense. But they talk about very different aspects of the simple present is used for things that are true in general, or happen repeatedly. Think about this as a big, wide present tense. Birds fly. The sky is blue. I like grapes. I have a dog. On the other hand, the present continuous is often used for right now, the exact current moment. This is a small present tense. There is a start and an end. It is happening right now but it will stop in the future. I am reading. It is raining. My sisters are talking. FormWhen you are making an affirmative statement, the simple present is just a single word, either the base form of the verb or with a final -s after the subject pronouns he, she, it, or a singular noun. I watch TV. He exercises. I am watching TV. He is exercising. Signal WordsThe simple present tense is often used with adverbs of frequency always, never, sometimes, frequently, rarely. I always brush my teeth. I never eat bacon. I go to the beach sometimes. I exercise frequently. I rarely watch TV. The present continuous is often used with adverbs and adverb phrases that emphasize the current moment or that a situation is only temporary, such as right now, at the moment, currently, and for the time being. I'm sitting in traffic at the moment. For the time being I am living in Brooklyn but we will move in September. Right now I'm studying. I am having dinner at the moment. ExceptionsNote that some verbs called non-continuous verbs or stative verbs describing feelings, senses, states of mind, and states of being are generally used in the simple tenses only, or else have a different meaning when used in the simple vs continuous forms. Simple Present and Present Continuous

Thereare three types of tenses; Present tense, Past tense and Future tense. But here we will discuss only the types, formation, and examples of Past tense. There are four types of Past tense; 1. Simple Past Tense. The simple past tense is used to describe an action that happened in the recent past. The simple past tense is also called the past

^{PresentPerfect Continuous of my sweet but horrible series was uploaded yesterday but needed some alteration and therefore was deleted after an hour. So this is NOT A REPEAT. I have made some necessary alterations plus comparisons with other Present Tenses to clarify and ensure the correct use of the tense. Signal words of both Pr. Perfect / Pr. Perf. Cont is given together with its normal and}

Myquestion: In this statement you would have used, this year instead of last year.because you're talking about present perfect continuous tense. July 22, 2017 at 11:16 PM Unknown said

AdapunSignal Time dari Simple Present Continuous Tense adalah now, currently, at this time, at present, at this moments, and nowadays. Dengan begitu, kita akan lebih mudah ketika akan mengubah Kalimat Aktif ke Kalimat Passive ataupun sebaliknya ya.

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time signal simple present continuous tense