题目内容：

还比较简单的,看看
1,__we swim in that river?No,you __.It's dangerous to swim here.
A ,Must,can't B,Can ,may not
C,Shall,don't D,May,must't
2.Could I look at your pictures?-----Yes,of course you___
A,could B,can C,would D,must
3.___I leave all the books here ----Sorry ,you can't.You have to take them back home
A,Need B,Must C,May D,Should
4.Can you finish the work in three days?----Sorry,I ___.It's too hard
A,mustn't B,may not C.can't D,needn't