Ответ:

1) I have already met Mr. Ben and his son.

2) Lera has learnt English before.

3) I have been to London.

4) She has already finished.

5) She has been late again.

6) He hasn't been late this month.

7) They haven't finished yet.

8) I haven't been to Russia.

9) Lisa hasn't learnt English before.

10) I haven't met Mrs. Vika and her son yet.