Past simple vs. present perfect

Introduction

(For form and practice specific to each tense, please see the past simple and present perfect worksheets).

The present perfect tense is used

to describe past experiences
for something which started in the past and is still true
to describe changes.

When we use the present perfect tense we cannot say when something happened. It is used to talk about non-specific time or a period of time.

The past simple tense is used

for finished actions in the past
for habits in the past
for past facts
for periods of time in the past.

We can use the past simple tense to talk about a specific time or a period of time.

Example 1

Present perfect
- I have lived in Hong Kong for 17 years.
Past simple
- I lived in Hong Kong for 17 years.

In both examples, the period of time is 17 years. However, in sentence 1, because we use present perfect, we know that the action continues. The person still lives in Hong Kong.

In sentence 2, we use past simple, therefore the action is finished. The person lived in Hong Kong for 17 years but now lives somewhere else.

Example 2

Present perfect
- Peter has been to India twice.
Past simple
- He went there in 1992 and in 2004.

Sentence 1 talks about Peter's experiences. We know that he has visited India twice, so far.

Sentence 2 tells us specifically when he went to India.

Example 3

Present perfect
- Tom and Sue have worked at the company since 2001.
Past simple
- Tom and Sue started working at the company 13 years ago.

Sentence 1 uses present perfect with since. We know that they started working there in 2001 and continue to work there.

Sentence 2 uses past simple with ago. "Ago" is like saying "before": it is used to show how long before the time of speaking the action happened. So, "two years ago" = "~~two years before~~". But we say "ago" not "before".

Both sentences tell us when Tom and Sue started working at the company, but in different ways.

Expressions of time

Expressions of time with the present perfect tense:

"since"	We use "since" + a specific moment in time: since 1963, since last year, since the holidays, since my childhood, etc.
"ever"	This means "at any time": Have you ever seen a wild dolphin?
"already"	The action is done by or before a stated or implied time or the action is done earlier than expected: We have already sold the house.
"just"	The action was completed a short time before: I have just eaten dinner.
"yet"	Up to that point in time: He hasn't started work yet.
"still"	This shows that a situation continues, usually when we expect it not to I still haven’t received the letter.

Expressions of time with the past simple tense:

"ago"

"yesterday"

"last Monday"
"last week"
"last month" etc

a date
a year

Expressions which can be used with both tenses:

"for" + period of time	We use "for" + a period of time: for six weeks for 2 months for ten years for the weekend, etc.
"recently"
"never"	This means "not at any time": I have never seen a wild dolphin. I never visited the Taj Mahal when I lived in India.