_______ is very important for us students to learn English well.

—How do you find your new classmates?—Most of them are kind. But _________ is so good to me as Bruce. 

— Finished?— No, I’ve got __________________three questions to answer.

---Susan, go and join your sister cleaning the yard. --- Why ___? John is sitting there doing nothing. 

Who can you turn to in time of danger, it not ________.