The students were sitting in the classroom with their eyes　　　on the teachers.

This is a very serious matter and the Chinese Academy of Sciences is trying to             public awareness about it.

—Don’t you know your computer has been inflected with viruses? — Really？No wonder it hasn’t_______ as properly as before.

．Our teacher is very busy.He is ________ in working out a teaching plan.

 It doesn’t _____ if you are late to my party. I just want you to come.