关于形容词比较等级

题目

关于形容词比较等级
I'm not sure if Mary can sing _____ Mabel.
A as good as B as well as C so good as D as better as
为什么

答案

选 B
I'm not sure if Mary can sing _as well as_ Mabel.
这里sing动词后用副词,good 应该为well.