— Susan, would you like to go hiking with us this afternoon?— I'd love to, but I study for a test.A. may B. have to C. can
-George is not here. What’s the matter with him?-Her father is ill in hospital. She has to_____ him.
Mike went to the library ____ some books the day before yesterday.
Nancy _____ playing the piano at 7pm. yesterday.
The Great Wall of China is ______wall in the world.
_____ is not difficult to learn English well.