Question

89. To save money for my education, my mother often takes on more work _____ good for her.

A. than what is B. than that is C. than it is D. than is为什么选b，请细讲，谢谢！

Answer 1

这道题我查了一下网上的资料选D
than作关系代词时，一般用在形式为比较级的复合句中，其结构为形容词比较级（more）．．．than＋从句，than在从句中作主语，相当于that，代表它前面的先行词。than 作关系代词，先行词就是more work，所以就不需要that, it等代词了。
比如：You spent more money than was intended to be spent.
你花的钱超过了预定的数额。（than是关系代词，在句中作主语,其先行词是money）