This kind of CD-ROM is very popular. Why not buy one before it___________?A. comes out B is come out C. is sold out D. sells out
On holidays, they prefer to ______ at home rather than ______.
—Could you help me carry this box? It’s too heavy. —__________.
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!