it做形式主语用法大全
动词不定式,动名词或主语从句作主语时,通常把它们放在谓语动词前,而用it作形式主语,放到句首,常见句型有:
1. It + be + 形容词+主语从句,如:
It is uncertain whether he can come to Jenny’s birthday party or not.
2. It + be + 名词词组 + 主语从句,这类名词有:a fact, a pity, a shame, an honour,a question等,如: