Professor Li has two daughters,both of ________ are middle s

Professor Li has two daughters,both of ________ are middle school students.A.who B.which C.them D.whom The soup is very salted.You ______ a lot of salt in it.A.should put B.could have put C.might put D.must have put The problem is ______serious ______we haven’t found the way to solve it.A so,that B so,as C such,that D such,as 答案(为什么选);解释(为什么不选)翻译