|
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： 形容词+主语从句 ， It is uncertain whether he can come to Jenny’s birthday party or not. It + be + 形容词 + （for sb.）+ 动词不定式 等作表语， *这类句型常用形容词 easy, difficult, hard, important, possible，wise 等， *为了强调不定式动作的执行者， 为了强调不定式动作的执行者，常在不定式前加 for sb， 如： It’s necessary for the young to master two foreign language. It is unwise to give the children whatever they want. It + be + 形容词 + (of sb.) + 动词不定式， *这类形容词常是表示心理品质 性格特征的 如：kind, nice stupid, clever, foolish, polite, impolite, silly, selfish, considerate 等。 *某人和这些形容词可以构成主系表结构。 如： It’s very kind of you to help me with the work. =You are kind to help me. It seemed selfish of him not to share his dictionary with others. =He seemed selfish not to share his dictionary with others. (3)It + be +名词词组 + 动词不定式， It is not a good habit to stay up too late. | 
