介词与句子搭配问题

He always thinks__________ he can do more for the people
A.of how
B.how

C.of that

D.why
答案是A，为什么要加of？
还有Sit wherever you like，为什么不加in或on？

To be or not to be，that is a question.

是不是因为第一个题是名词性从句而第二个是状语从句？

To be or not to be，that is a question.