1.若是Vt+名词(O)+形容词(OC),则不可用形式宾语(it),例如：
He made his intention clear.
I will keep myself warm in the heavy clothing.
They held her story true after hearing it.
Fast transportation has made the round trip possible.
2.但宾语是不定词或名词子句时,须用形式宾语(it),写成Vt+it (虚O)+形容词(OC)+ 不定词或名词子句(真O),例如：
He made it clear what he intended to do.
They feel it necessary to work harder.
Airplanes make it possible to travel around the world in a short time.
3.前例2全部it (虚O)不能省略.为何用虚宾语(it)呢?因为真宾语太长,试看：
(X) Airplanes make to travel around the world in a short time possible.
现行英语不成立.