Why did you go back to the library—Oh，I left my classmate Julia there.

Thanks a lot, Mr. Wang. I don’t know how to ________ the help you gave me during my stay here.—It’s my pleasure. Welcome to China again when you have time.

The children _____long wool coats stopped to look at us.

Miss Li is ______ favorite teacher .She likes _______.

It is generally believed that Watson and Crick’s discovery about DNA was ____ beginning of _____ enormous advances in _____ field of genetics.