there isn't much ___ i can do

问题描述:

there isn't much ___ i can do
a.which b.what c.that
为什么选C?

这个是定语从句 much是先行词而that的从句是修饰much的,所以不能选what
而且有much的句子只能用that不能用which
还有something ,nothing,the one等等都只能用that