Did you find --- very interesting to play Yo-Yo.应填什么?

it
.宾语是不定词或名词子句时,须用形式宾语(it),写成Vt+it+形容词+ 不定词或名词子句.比如说:
He made it clear what he intended to do.
I take it for granted that you will give me a hand.
They feel it necessary to work harder.
在以上句子中,真正的宾语都不是it,而是句子的后半部分.
2.你所提到的问题不是能不能接宾语从句的问题,只是一种习惯表达方式.用形式宾语更简洁明了,而且形式宾语就是宾语从句的省略形式.比如可以说：
I think it is difficult for me to explain this to you.
就可以直接说成
I think it difficult for me to explain this to you.