★Present perfect and past simple

★ Present perfect and past simple ★

Tom is looking for his key. He can't find it. He has lost his key.
This means that he doesn't have his key now.

*Ten minutes later
Now Tom has found his key. He has it now. Has he lost his key? No, he has found it.
Did he lose his key? Yes, he did.
He lost his key (past simple)
but now he has found it. (present perfect)

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The present perfect (something has happened) is a present tense. It always tells us about the situation now.. 'Tom has lost his key' = he doesn't have his key now.

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The past simple (something happened) tells us only about the past. If somebody says 'Tom lost his key', this doesn't tell us whether he has the key now or not. It tells us only that he lost his key at some time in the past.

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Compare

☆They've gone away. They'll be back on Friday. (They are away now)
★ They went away, but I think they're back at home now. (not They've gone)

☆ It has stopped raining now, so we don't need the umbrella. (It isn't raining now)
★ It stopped raining for a while, but now it's raining again. (not It has stopped)

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→Use the present perfect for new or recent happenings:

☆'I've repaired the washing machine. It's working OK now.' 'Oh, that's good.'

☆'Sally has had a baby! It's a boy.' 'Thats's a great news.'

→Usually, you can also use the past simple:

☆I repaired the washing machine. It's working OK now.

→Use the past simple (not the present perfect) for things that are not recent or new:

☆ Mozart was a composer. He wrote more than 600 pieces of music. (not has been... has written)

☆My mother grew up in Italy  (not has grown)

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Formation: 

Subject + has/have + past participle ⇾ PRESENT PERFECT

Subjetc + verb in past form ⇾ PAST SIMPLE