题目内容：

1.The plant is dead.I( )it more water.
A.will give B.would have C.must give D.should have given
2.Such a small child as he ( )a ticket.
A.mustn't have B.can't have C.needn't to have D.doesn't need
3.The problem（）at the meeting now is seriousto us.
A.to be doscussed B.being discussed C.discussed D.discussing
4.The picture () on the wall is painted by my nephew.
A.having hung B hanging C.hangs D.being hung
请大虾们一定要详细写下过程.还有考的是哪个知识点,

优质解答

1 D.本来应该,虚拟语气
.
2 D,need为实意动词.mustn't不可以；can't不能；needn't to have 中need为情态动词,应接动词原形.
3 选B 因时间状语为now.A,将被讨论.后三者依次为正在被讨论、讨论过了、讨论主动态.
4 D.悬挂的过去分词为hung,被悬挂,所以选最后.