A: We
use the present perfect when we talk about something that happened in a
period of time up to the present. We
use the past simple to talk about something that happened at a particular, finished time in the
past. Compare:
Ex: Science
has made many major advances this century, and
Scientists
made some fundamental discoveries in the 18th century.
He
puts to good use things that other people have thrown away,
and
I threw
away most of my old books when I moved house.
When we report that someone has recently
invented, produced, discovered or written something we use the present perfect.
When we talk about something that was invented, etc. in the more distant past
we use the past simple. Compare:
Ex: Scientist
have discovered that, all over the world, millions of
frogs and toads are dying.
It is often said that Hernan Cortes 'discovered' Mexico
in 1519.
Two schoolchildren have invented a device for moving large objects up flights of stairs.
Chinese
craftsmen invented both paper and printing.
B: We
can use either the present perfect or the past simple to talk about repeated
actions or events. If we use the present perfect, we often suggest that the
action or event might happen
again.
Sometimes we emphasize this with phrases such
as so far and up to now. If we use the past simple, it
suggests that it is finished and won't
happen again. Compare:
Ex: Timson
has made 13 films and I think her latest is
the best, and
Timson made 13 films before she was tragically killed in a car accident.
Lee has represented his
country on many occasions, and hopes to go on to compete in the next Olympics, and
Lee represented his
country on many occasions, but was forced to retire after an injury.
C: We
can use both the present perfect and the past simple to talk about states. We use the present
perfect to talk about a state that existed
in the past and still exists now, and we use the past simple if the state no longer exists. Compare:
Ex: I have
known him most of my working life. (I am still working) and
I knew
him when we were both working in Rome.
We have belonged to
the tennis club since we moved here. (We still belong to it.) and
We
belonged to the tennis club in the village we
used to live in.
D: Time adverbs that
refer to the present, such as today, this
morning/week/month, can also be used with either the present perfect or past
simple. If we see today etc. as a past, completed period of time, then we use the past
simple; if we see today, etc. as a period including the present moment, then we use the present
perfect. Compare:
Ex: I didn't
shave today (= the usual time has passed;
suggests I will not shave today) and
I haven't shaved today. (= today is not finished; I
may shave later or may not)
I wrote three letters this morning. (= the
morning is over) and
I've written three letters this morning. (= it is still
morning)
E: We use since to talk about a period that started at some point in
the past and continues until the present time. This is why we often use since with the present perfect:
Ex: Since 1990 I have lived in a small house near the coast.
Tom has been ill since Christmas.
In a
sentence which includes a since-clause, the usual pattern is
for the since-clause to contain a past
simple, and the main clause to contain a present
perfect:
Ex: Since Mr Hassan became president, both taxes and unemployment have
increased.
I
haven't been able to play tennis since I broke my arm.
However, we
can use a present perfect in the since-clause if the two situations
described in the main and since-clause extend until the present:
Ex: Since I've lived here, I haven't seen my neighbors.
F: We use the present perfect with ever
and never to emphasize that
we are talking about the whole of a period of time up until the present:
Ex: It's one of the most magnificent views I have
ever seen. (= in my whole
life)
I've never had any problems with
my car. (= at any time since I bought it)
We use the past
simple with ever and never to talk about a completed period in the past:
Ex: When he was young, he never bothered too much about his
appearance.
EXERCISES
I- Complete these sentences with the verb given. Choose the present perfect
or past simple.
1- According to yesterday's newspapers, astronomers in Australia___________
a planet in a galaxy close to our own. (discover)
2- To help today's customers make a choice, a company in New York
___________________ a video trolley a supermarket trolley with a video screen
to display advertisements and price information. (develop)
3- At the start of his career, Cousteau ____________________ the
aqualung, opening the oceans to explorers, scientists, and leisure divers. (invent)
4- He proudly told reporters that the company __________________
software to prevent the recent increase in computer crime, (produce)
5 John Grigg _________________ the comet now called Grigg-Skjellerup, at
the beginning of the 20th century. (discover)
II- Complete the sentences with appropriate verbs. Use the
same verb for each sentence in the pair. Use either the present perfect or the
past simple.
1- a: A lot of people_________________
about the painting, and I always say it's not for sale.
b: The police
______________ me several questions about my car before they let me go.
2- a: Until she retired last month, she__________________ in the
customer complaints department.
b: Sullivan
__________________ hard to change the rules and says that the campaign will go
on.
3- a: I _______________ skiing ever since I lived in Switzerland.
b: She once
__________________ the support of the majority of the Democratic Party.
4- a: His father ________________ so many complaints about the noise
that he told Chris to sell his drums.
b: We
________________ over 50 letters of support in the last 10 days.
5- a: The Bible __________________ more copies than any other book.
b: When it
became clear that we would be moving to Austria, we __________________ the
house to my brother.
6- a: I ___________________ moving to London from the day I arrived.
I'd love to go back to Rome.
b: At first I
__________________ inviting them to stay, but we soon became great friends.
I- Compare
the use of the present perfect continuous and the present perfect:
Present Perfect continuous:
Ex: The guests have been arriving since about 6 o'clock.
Since
the operation two months ago, Joe has been learning to walk again. He can already take two or three steps
unaided.
She's been driving for 3 years now.
Present perfect:
Ex: Mark and Helena have arrived - they're in the sitting room.
I have learnt a lot about
painting from Paul.
We have driven all the way here without a break.
@We use both the present perfect continuous and the present
perfect to talk about something that started in the past and which
affects the situation that exists now. The difference is that the present
perfect continuous focuses on the activity or event which may or may not be finished. The present perfect, however,
focuses on the effect of the
activity or event, or the fact that something has been achieved.
Sometimes the difference
between them is simply one of emphasis.
Ex: I've been following their discussions with great interest, (emphasises the activity; that is, my following their discussions)
I've followed their
discussions with great interest, (emphasises the result; I may now react to what was said or decided)
II- We can use either
the present
perfect continuous or the present perfect to talk about
activities or events that are repeated again and again until now:
Ex: Joseph
has been kicking a football against
the wall all afternoon, (or ...has kicked...)
The press has been
calling for her resignation
for several weeks, (or ...has called...)
@ However, if we mention the number
of times the activity or event was repeated, we use the present
perfect rather than the present perfect continuous:
Ex: I've bumped into Susan 3 times this week.
He has played for the national team in 65 matches so far.
III- We use the present
perfect rather than the present perfect continuous when we
talk about long lasting or permanent situations, or when we want to emphasize
that we are talking about the whole of a period of
time until the present.
Ex: I have
always admired Chester
They are the most delicious
oranges I've ever eaten.
@ When we talk about more temporary
situations we can often use either the present perfect continuous or the
present perfect:
Ex: 'Where's Dr Owen's office?' 'Sorry, I don't know. I've only
worked / I've only been working here for a couple of days.'
III- When we want to emphasize
that a situation has changed over a period of time up to now, and may continue
to change, we prefer the present perfect continuous to the
present perfect:
Ex: The pollution problem has been
getting worse over the
last decade.
Sales have been
increasing for some time.
However, if
we talk about a specific change over a period of time which ends now, particularly
to focus on the result of this change, we
use the present perfect.
Ex:
Prices have
decreased by 7%. {= in a period
up to now)
The
population has grown from 35 million in 1950 to 42 million today.
EXERCISES
1- Complete the sentences with these verbs, using the
same one for each sentence in the pair. Use the present perfect in one sentence
and the present perfect continuous in the other.
claim
disappear give move stop
1- A: An important file from
my office.
B: Plants and
vegetables from my garden since we had new neighbours.
2 -A: Dr Fletcher the same lecture to
students for the last ten years.
B: Mr Goldman
nearly a million pounds to the charity this year.
3-A: With their win yesterday, Italy
B: As house prices in the cities have risen, people into
the countryside.
4 A: For years he that he is related to
the royal family.
B:
The earthquake over 5000 lives.
5-A: All day, the police motorists to
question them about the accident.
B:
Good, the noise I can start concentrating on my work again.
2- Choose the most appropriate sentence ending.
1- I've swum... a- and I feel exhausted,
2- I've been swimming... b- thirty lengths of the pool.
3 They have asked me... a- to visit them
for ages, but I've never had the time,
4 They have
been asking me... b- to join the
company on a number of occasions.
5 I have
visited Vienna
6 I've been visiting Vienna
7 We've
stayed... a at
this hotel a couple of times before,
8 We've been
staying... b at a small
hotel near the sea.
3- Complete
these sentences using the verb given. If possible, use the present perfect
continuous; if not, use the present perfect. Use /, to add any words outside the space.
1- Since
they were very young, the children _____________________ (enjoy) travelling by plane.
2 -It ________________________(snow) heavily since this morning.
3 - I'm pleased to
say that the team _________________ (play) well all season.
4- I never
_________________ (understand) why we have
to pay so much tax.
5- I __________________________(not read) any of Dickens' novels.
6- In recent years, Brazilian companies ___________________________(put) a lot of money into developing advanced technology.
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