Ответ:

Has he eaten a sandwich yet?

Yes,he has already eaten it.

Has he turned off the computer yet?

Yes,he has already fone it.

Has he drunk his coffee yet?

Yes,he has already done it.

Has he tidied his desk yet?

No,he hasn't.

Has he put away his CDs yet?

No,he hasn't.

Has he made his bed yet?

No,he hasn't.

Has he put away his clothes yet?

Yes,he has already done it.

Has he finished talking in the phone yet?

No,he hasn't.

B.

She has just failed an exam.

We have just had lunch.

He has just been on holiday.

She has just missed her train.

He has just woken up.