( ) 2.I think ______ necessary for us to solve.A.it B.that C.its D.that’s为什么选A,不选D
问题描述：
( ) 2.I think ______ necessary for us to solve.A.it B.that C.its D.that’s
为什么选A,不选D
答
it作think的宾语，另一说法：I think it is necessary for us to solve.
答
这是一个固定搭配it is +形容词 for sb to do sth.所以用IT
答
it
it 作形式宾语，真正的宾语是动词不定式。而且，necessary作宾语补足语。相当于 it is necessary for us to solve。
答
it做形式主语
答
A 句型it is necessary for sb to do sth 对某人来说做某事是必要的 it作形式主语,to do是实际主语