名词性从句的几道选择题

名词性从句的几道选择题
先是名词性从句
______do you think __we should do to improve our English?
a.what that b.what /
为什么选b不选a?
It is generally considerd to be of improance __ a person __good examples.
a.what follow b.that follow
完全没看懂这句是什么意思?为什么选b不选a
He wanted to know__Disneyland.
a.how much it cost to visit
I really don't know __with the litter girl.
a.What was the matter.
什么时候用正常语序啊?
那什么时候是正常语序,什么时候不需要呢?