—You________ tell Jack the bad news. He is very busy now. —OK. A. must B. can C. had better not
People should __________ from __________ down the trees to protect the earth.
I don’t think you can finish the work in such a short time, __________?
__________ useful advice he has given us!
I didn’t know when he _____ back. He said he would call me when he _____ home.
Four days __________ enough for us. We still need ________ two days.