— Could I borrow your dictionary?— Of course you ______. 

I          use a clock to wake me up because at six o'clock each morning the train comes by my house.

—Must we clean the classroom now?—No ,you _______.

-Is the man over there your English teacher ? --No, it ______ be him. He has gone to Canada to study further.

－I’d like to help the homeless people in the earthquake. －You ________ join a volunteer group.