Пожалуйста помогите !!! Исправьте грамматические оплошности!!!

1. let's meet at five o'clock.
2. they are having dinner now.
3. will you go to the library after classes tomorrow?
4. did you get up this morning at 7 o'clock?
5. I didn't meet my best friend yesterday.
6. i have already done my household duties.
7. he did not visit the british museum.
8. we are talking about famous writers now.
9. we have already come there. we have not come there yet.
10. when i will return i shall call you then.