Question

She didn't know________. A.what she could do it

B.what to do it
C.what she can do
D.how to do it

Answer 1

选择D吧 她不知道怎样做（它）。
一般这一类的是这么记的。 she did't know what to do .do 后面没有宾语it 那么用what。其实what就是do的宾语。（她不知道做什么）。
还有一种是就是这个选择she didn't how to do it. do后面有宾语it，就选择how表示方式，怎么做的意思。（她不知道怎么做这件事）

另外 what to do 和how to do 都是疑问词+to do （动词不定式）的一个用法。

Answer 2

She didn't know________.
A.what she could do it
B.what to do it
C.what she can do
D.how to do it
选项是D

Answer 3

选C。 A、B、D选项都要去掉it。。
She didn't know what she could do.
她不知道怎么办。
望采纳，祝开心~！

Answer 4

D
宾语从句
可以用
What to do
How to do
How to do it
What she could do
这四种情况

Answer 5

D.
A.B后去掉it 就对了，C时态不对，应该是what she could do.所以选D。
通常用法是what to do How to do +宾语

Answer 6

D.how to do it 。有what时do后不能有it，didn't是过去时C改成could才对