e+形容词+不定式 eg:It’s better to be early.
be+名词+不定式 eg:It was his duty to take care of the orphans.
be+介词短语+不定式 eg:It’s beyond me to say why.
It + 及物动词+宾语+不定式 eg:It makes me sick to think about it.
be+名词+动名词 eg:It’s no good standing here in the cold.
be + 形容词+动名词 eg:It’s helpless trying to convince her.
其他结构+动名词 eg:It doesn’t matter waiting a few more days.
