—Alice, why aren’t you at work today?—I       a day off．

It is well known to us all that a lot of rivers _______by factories.

---- The battery in my cell phone is running low. ---- I _____ that last night before we went to bed.

I first met Mr. Smith in America. He ______ at Stanford University then.

With the development of modern society, E-mail as well as telephones     an important part in daily communication.