We form the present perfect simple with have/has and the past participle of the verb.
(pro)noun + have, has + past participle
We use present perfect for:
1. Actions which started in the past and still continue in the present:
He has worked as a doctor since 1990.
2. Actions which have recently finished and their results are still visible:
I have broken my arm.
He has tried rock climbing.
4. Actions which happened at an unspecified time in the past. The exact time is not mentioned:
Adam has bought a new mobile phone.
Affirmative: (pro)noun + have, has + past participle
I have finished my homework.
Negative: (pro)noun + have, has + not + past participle
I haven't finished my homework.
Interrogative: Have, has + (pro)noun + past participle
Have you finished my homework.
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