帮我分析一下这句话的语法成分,

问题描述:

帮我分析一下这句话的语法成分,
and the average working women is likely to earn only about half ____ a man earns for the same job.
A.than B.that C.which D.what
为什么A不行
用that不充当句子成分,不也可以吗?敢为这是一个什么从句啊

从证据上看half后面应该加名词.选项里没有,所以只能是 代词 做转换.所以选D
例如:he only got the half what he had last year他只可到了去年的一半.