Knowing how to use the Verb Tense correctly is an important part of GMAT sentence correction preparation. A Tense error on GMAT could be as straight-forward as using the present tense instead of the past tense. For example, 

saying 'Anna goes to the market yesterday' instead of 'Anna went to the market yesterday'. 

But we have seen many questions on GMAT where some options use the simple tense where as othes use the perfect tense. 

What if you were asked to choose between 

'Anna went to the market yesterday' and 'Anna had gone to the market yesterday'

Hence it is important to know the difference between the tenses.

1. What is the Present Perfect Tense

In order to identify the use of the Present Perfect Tense, we need to look for a combination of

has or have + Verb (in its participle form)

For example:

has gone , has worked , have eaten ,  have played  are all in the Present Perfect Tense.

The following sentences are all in the Present Perfect Tense

He has worked here all his life.

They have worked very hard on this project.

She has done her homework.

We have been living here since 2010.

When to use the Present Perfect Tense?

There are 3 situations in which the Present Perfect Tense can be used.

1. When the time frame within which a past event is mentioned is still going on

Look at the examples below:

Incorrect: There were two major elections this year.

Correct: There have been two major elections this year.

Here, the events (elections) have occurred in the past. However, the time frame of the sentence ('this year') is still going on. In such cases, we cannot use the Simple Past Tense. We have to switch to the Present Perfect Tense.

2. When there is no reference to time in the sentence for a past event

Look at the examples below:

Incorrect: They visited Switzerland many times.

Correct: There have visited Switzerland many times.

Here, the events (visits to Switzerland) have occurred in the past. However, there is absolutely no time reference in the sentence. In such cases, we cannot use the Simple Past Tense. We have to switch to the Present Perfect Tense.

However, if we provide a time reference in the past, then the Simple Past Tense has to be used.

Incorrect: They have visited Switzerland many times last year.

Correct: There visited Switzerland many times last year.

3. When the event begins in the past but continues into the present.

Look at the examples below:

Incorrect: There are many lockdowns worldwide since the Covid-19 outbreak.

Incorrect: There were many lockdowns worldwide since the Covid-19 outbreak.

Correct: There have been many lockdowns worldwide since the Covid-19 outbreak.

Here, the events (lockdowns) started in the past (after the Covid19 outbreak), but have been continuing till date (the word 'since' implies this). In such cases, we cannot use either the Simple Present Tense or the Simple Past Tense. We have to switch to the Present Perfect Tense. (the video explains the timeline for better understanding)

2. What is the Past Perfect Tense

In order to identify the use of the Past Perfect Tense, we need to look for a combination of

had + Verb (in its participle form)

For example:

had gone , had worked , had eaten ,  had played  are all in the Past Perfect Tense.

The following sentences are all in the Past Perfect Tense

The train had left when I arrived at the station.

The student was scared because he had not done his homework.

I had sold off most of my stocks before the market crashed.

When to use the Past Perfect Tense?

The Past Perfect Tense is used to refer to an event that has occurred before another event in the Past.

i.e. when we want to show that one event occurred earlier than another.

(the video explains the timeline using multiple examples for better understanding)

Let us revisit the 3 sentences given above.

The train had left when I arrived at the station.

There are 2 past events here - the train leaving and my arriving at the station. We want to show that by the time I arrived, the train had left. So the event that occurred earlier in time (i.e. the train had left) is expressed using the Past Perfect Tense where as the other past event (I arrived) is expressed in the Simple Past Tense. 

The student was scared because he had not done his homework.

There are 2 past events here - the student being scared and the student not doing his homework. We want to show that the action of not doing the homework earlier in the past was what led to the student being scared later in past. So the event that occurred earlier in time (i.e. had not done) is expressed using the Past Perfect Tense where as the other past event (was scared) is expressed in the Simple Past Tense. 

I had sold off most of my stocks before the market crashed.

There are 2 past events here - my selling of the stocks and the crash in the markets We want to show that by the time the markets crashed, I had sold off my stocks. So the event that occurred earlier in time (i.e. sold off the stocks) is expressed using the Past Perfect Tense where as the other past event (markets crashed) is expressed in the Simple Past Tense. 

Finally, coming back to the choice between 

'Anna went to the market yesterday' and 'Anna had gone to the market yesterday'

we have to take note of the fact that in the above example, the act of going to the market does not preceed any other event. In fact, there is just one event occurring in the sentence. In such cases, the Past Perfect Tense cannot be used.

Correct: 'Anna went to the market yesterday'

Incorrect: 'Anna had gone to the market yesterday'