问3道英语选择题1.In such dry weather,the flowers will have to be wa

问3道英语选择题
1.In such dry weather,the flowers will have to be watered if they( )
A.have survived B.would survive C.will survive
2.What( )has been finished.
A.will do B.should be done C.should do D.must do
3.All the books( )out of the reading room.
A.mustn't be taken B.mustn't take C.can't take D.must not to be taken
并说一下为什么