Can I come this afternoon or tomorrow morning?–is OK.I’m free today and tomorrow.

I can think of many cases _____ students obviously knew a lot of English words and expressions but couldn’t write a good essay.

_______ do you help the old man with the housework?-Once a week. [ ]

Look at the picture on the wall. It ________be David’s.—Yes, his name is on the first page.

It’s reallythat a tortoise can150 years old.