题干
—Shall we have a smoke here?
—No, we _____ because this is gas station and the worker is carrying some petrol.
A：can't
B：needn't
C：mustn't
D：won't
答案(点此获取答案解析）
C
It is noon now. The sun is high in the sky. It is very hot. Look at the tree. The shadow is short. 
It is evening now. The sun goes down in the west(西方). Look at the tree, the shadow is long again. 
It is night now. The moon is high in the sky. There are some stars in the sky too. 
