Question

Alice didn't want her parents to know______ A how she had done B what she was doing

我知道答案是B，但是说不出A为什么不行，请大家从语法角度给我分析一下。

Answer 1

do是一个及物动词，后面要接宾语，而how是一个疑问副词，不能作动词的宾语，所以how she had done ，这句话存在了语法错误。
只能选择B.

Answer 2

爱丽丝不想让她家长知道她在干什么。
如果选A，意思就变成了“怎么做的”，但是问题是本句中的done后面少了个宾语，如果加上个类似 it 这样的词就可以了，...how she had done it. 怎么做的这件事。

Answer 3

know 这里是及物动词，后面必须加宾语 所以是B 或者是how she had done it