Tommy, you____ be hooked on the Internet all day. You may fall behind others in study.
| A．mustn’t | B．shan’t | C．can’t | D．needn’t |
31. Do you know when did the world _____?
| A．come into being | B．come | C．formed | D．Existed |
30. The coal we use today should _____ plants and trees.
| A．begin with | B．start with | C．commence as | D．originate as |
29. That's all for the party. Let's _____.
| A．fall asleep | B．go to sleep | C．go to bed | D．be asleep |
28. They ____ friends since they met in Shanghai ten years ago.
| A．have become | B．have turned | C．have been | D．have grown |
27. When he heard the news, his heart ______ very fast.
| A．stroke | B．beat | C．knocked | D．Jumped |