it的用法考点典型陷阱题分析1. everyone knows that _______ is dangerous to play with fire, but _______ is difficult is to prevent children from playing with fire.a. it, it b. what, whatc. it, what d. what, it【陷阱】很容易误选b，认为两空均考查形式主语。【分析】最佳答案是d，第一空填形式主语，真正的主语是其后的不定式 to play with fire。第二空填 what，what is difficult 是主语从句，注意 what is difficult 后的谓语动词 is。请做以下类似试题：1 i know ______ is important to know my own limitations, but _______ is difficult is to help others to know their own limitations.
