Study this example situation:

Tom is looking for his key. He can't find it.
He has lost his key.

He has lost his key = He lost it recently, and he still doesn't have it.

Have/has lost is the present perfect simple:

The present perfect simple is have/has + past participle. The past participle often ends in -ed (finished/decided etc.), but many important verbs are irregular (lost/done/written etc.).

For a list of irregular verbs, see Appendix 1.

• Owl I've cut my finger.
• The road is closed. There's been (there has been) an accident.
• (from the news) Police have arrested two men in connection with the robbery.

• 'Where's your key?'  'I don't know. I've lost it.'  (=I don't have it now)
• He told me his name, but I've forgotten it.  (= I can't remember it now)
• 'Is Sally here?' 'No, she's gone out.'  (= she is out now)
• I can't find my bag. Have you seen it? (= Do you know where it is now?)

• James is on holiday. He has gone to Italy. (= he is there now or on his way there)
• Jane is back home now. She has been to Italy. (= she has now come back)

You can use the present perfect with just, already and yet.

• 'Are you hungry?' 'No, I've just had lunch.'
• Hello. Have you just arrived?

• 'Don't forget to pay your electricity bill.' 'I've already paid it.'
• 'What time is Mark leaving?' 'He's already left.'

• Has it stopped raining yet?
• I've written the email, but I haven't sent it yet.