Past simple
The past simple is often considered the default tense to talk about past actions and situations, i.e. we use it unless we have a particular reason for using another past tense. We often use it when we tell stories or when we describe past events, and we also often use it together with words or phrases referring to the past (e.g. two hours ago, yesterday afternoon, fast week, in 2009, when I was a child, etc). However, past time expressions (e.g. last year, two years ago, etc.) are not always in the sentence, e.g.
To everyone's surprise, Jill left the company.
This is the case when it is clear that the speaker is talking about the past.
Past simple vs present perfect simple: We use both these tenses to talk about actions that started or finished in the past. The main difference is that we use the past simple to describe actions that happened in a completed time period, whereas we use the present perfect when there is a connection with the present. When we use the past simple, our focus is on 'When?', while we use the present perfect to say something about 'now' in one way or another. Compare:
How many symphonies did Beethoven compose?
Have you heard Hefner's latest recording of Beethoven's symphonies?
Expressions like last year, in 1989, when I was a child, three months ago, etc. are about a finished time and are therefore always used with the past simple.
By contrast, expressions such as since, already, this week, never, ever, today, etc. connect the past to the present and are therefore used with the present perfect. Compare:
She went to Vietnam last year.
Have you ever been to Vietnam? (= Do you know Vietnam? / Can you tell me something about Vietnam now?)
The museum opened in 1977.
Tim has already visited that museum three times. (= So now he really knows it well.)
Past continuous
We use the past continuous to say that something was going on around a particular time in the past. What was the manager doing when you went into his office?
We often use the past continuous and the past simple together; the continuous form describes the background action or situation, while the simple form describes a shorter action or event that happened in the middle of it.
We first met while we were travelling around the world.
We can also use the past continuous to show that two or more actions were in progress at the same time.
While she was studying for her M.A., she was also working part-time.
In narratives, we often use the past continuous for descriptions, and the past simple for events and actions.
The rain was falling in torrents. The trees were swaying like windscreen wipers. Suddenly a figure appeared from behind the hedge.
We sometimes use the past continuous in phrases like I was thinking / wondering / hoping to make a request or a suggestion sound less direct.
I was thinking that it might be a good idea to leave earlier.
I was wondering if you'd like to join me for lunch.
Past perfect simple
We use the past perfect simple when we are already talking about the past and we want to refer back to an earlier point in time or period of time.
We arrived at the conference venue late. The first workshop had already started.
The boss wasn't in when arrived. He had just gone out.
Compare past simple and past perfect simple:
When I arrived, Diego left. (first I arrived, then he left, i.e, these two events are in chronological order)
When I arrived, Diego had left. (he had left before I arrived, i.e. the sequence of events is not chronological)
We often use the past perfect simple in reported speech, and with verbs like said, thought, informed, realized, etc.
They informed us they had found another supplier.
I realized I had left my wallet at home.
We also use the past perfect simple after words like it wish, etc. to talk about hypothetical actions and situations, i.e. to talk about things that did not happen.
If you had seen me last week, you wouldn't have recognized me. (= you didn't see me)
I wish you'd told me the truth. (= but you didn't tell me)
Past perfect continuous
We use the past perfect continuous to talk about actions and situations that started in the past and continued up until another time in the past. When we use it together with another verb in the past simple, there is often a relation of cause and effect between the two verbs.
Jane wasn't doing anything special when went round to her place but she was exhausted. She had been digging her garden.
Compare past continuous and past perfect continuous:
I went out. It was snowing. (= snow was falling)
I went out. It had been snowing. (= the snow had stopped falling, but there was snow on the ground)
Compare past perfect simple and past perfect continuous:
Emma had been reading reports all day, so she was in a bad mood.
Emma had read all the reports, so she knew the facts.
The continuous form stresses the continuation of an activity, whereas the simple form stresses the idea of completion.
