4. Look! That fellow is too sleepy to work. He ______ up reading until midnight.                    

      A. mustn't stay             B. mustn't have stayed

C. ought not to stay         D. should not have stayed

5. How _____ you say that you really understand the whole story if you have covered only part of the article?

  A. can      B. must        C. need          D. may

6. The Dragon Boat Festival _____ the beginning of the hottest season of the year.

  A. marks     B. makes      C. falls     D. comes