If their marketing plans succeed，they ________ their sales by 20 percent

It’s time to say goodbye to my school . I’ll alwaysremember the people ____ have helped me .

It’s no use over spilt milk

Robert is away. He _______ America since last week.

A cat, ______ it is a white one ______ a black one, is considered to be a good cat as long as it can catch mice.