This is one of the best books （ ）.
（A）that have ever been written
（B）that has ever been written
（C）that has written
（D）that have written
Great changes have taken place since then in the school （ ） we are studying.
（A）where
（B）that
（C）which
（D）there
He studied hard at school when he was young, （ ） contributes to his success in later life. 选项：
（A）as
（B）therefore
（C）which
（D）so that
