難度:★  考點:情態動詞的用法
	
	  1.You________stop when the traffic light turns red.
	
	  A.can  B.had better  C.need  D.must
	
	  2.When winter comes,days get______.
	
	  A.long and long  B.short and short  C.longer and longer  D.shorter and shorter
	
	  3.-Mum,must I stay there the whole day?
	
	  -No,you____________.You____________come back after lunch,if you like.
	
	  A.mustn't;can  B.needn't;must  C.needn't;may
        
