题目内容：

____ is known to everyone that Taiwan is part of China.
____ is known to everyone that Taiwan is part of China．
A．As B．Which C．It D．What
为何不选D?

优质解答

选择C
当主语部分太长时为了句子平衡采用it作形式主语.所谓形式是指句子的真正主语将在句子末段出现.