Past tense VS present perfect tense

Dear Dr English,

Could you please explain in which situation we should use past simple tense and in which past continuous, and also in which situation present perfect tense is used? I am always confused whether to use past simple tense or present perfect tense. Please give some examples.

Suwanne Mekhumphan

Most Thai learners of English know the structures of tenses very well; their big problem is how to use these tenses correctly in context.

When we talk about an activity that happened and finished before now, we talk or write about it in past tense; present perfect tense refers to a past event which has a result in the present. Compare the following sentences:

Keith has fixed his toy plane. (His toy plane is all right again.)

Keith fixed his toy plane. (His toy plane may be broken again.)

The first sentence tells us that the action happened in the past and that the result is that the toy plane is all right again.)

In the second sentence, we only know that the action happened in the past. By now the toy plane may be broken again. It does not tell us anything about the present. Look at more examples:

Keith has bought a new yo-yo. (He bought a yo-yo, and it is his now.)

Keith bought a new yo-yo last Saturday. (The purchase happened at a specific time in the past.)

Sally, would you like something to eat? - No, thanks. I've eaten already. (Sally had something to eat, and now she is full.)

In our daily life, quite often while we are engaged in one activity, another event happens. We use the past continuous tense to say that a person was in the middle of an action when another event happened.

It was in the winter of 1981; I was doing my newspaper round in the morning as usual when I met your mother for the first time.

Most employees were having lunch when the fire broke out.

Past continuous is also used to refer to a temporary circumstance connected with a particular person or event in the past.

Jane and Rob were living in Melbourne during the first four years of our marriage.

Many flood victims were standing on rooftops for three days.

Past simple is for a completed action.

William graduated three years ago.

I had my hair cut yesterday.

The above comparisons should show you the difference between the two tenses and enable you to choose the correct one. Good luck!

By Dr English

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