50.　 Many of the stars________ because they are far away from us.

A. may not see　　　　 B. can not be seen

C. mustn't be seen　　　　 D. needn't see

49.　 Do you know________?

A. if it will be fine tomorrow　　　　　　 B. where did they see her

C. when shall we have a picnic　　　　　 D. which would you like

48.　 -How long have you________?

-Since 1990.

A. bought the MP3　　　　　 B. joined the Party

C. become a midfield player　　　　 D. lived in the town

47.　 The sick woman is________weak________ look after herself.

A. too;　　 to　　　 B. so;　　 that　　　 C. very;　　 to　　　 D. so;　　 to

46.　 Please don't leave until your teacher________back.

A. will come　　　　　 B. came　　　　 C. comes　　　　　 D. is coming