1.Helen was much kinder to her youngest son than to the others,-------,of course,made the others envy him.
A.who B.that C.what D.which
2.It is easy to do the repair.-------you need is a hammer and some nails.
A.Something B.All C.Both D.Everything
请详细解答，谢谢

1 D
which指代前面这句话“Helen was much kinder to her youngest son than to the others”，是这件事使别人嫉妒小弟弟，而不是小弟弟本身令人嫉妒，因此不选A,这不是主语从句，是定语从句，当然不能选C，而B项显然也不能指代前面的一整句话
Helen was much kinder to her youngest son than to the others,which,of course,made the others envy him.
可译为：Helen对待他的小儿子比对其他的孩子都好，这当然使得其他的孩子都嫉妒这个小弟弟

2 B
It is easy to do the repair.All you need is a hammer and some nails.
可译为：这很容易修理，你只需要一把锤子和一些钉子。
主语从句
all (that)=what
what you need is... =all you need is...