1.It's+形容词+of+sb.+动词不定式"某人(做某事)……",说明"人"的性质或特征。 常用形容词有:good,kind,nice,polite, clever, foolish, lazy, careful, careless, right, wrong等 It's very kind of you to help me. It's foolish of you to make such mistake. 2.It's+形容词+for+sb.+动词不定式 "做某事对某人来说……", 说明动词不定式的性质、特征。 常用形容词有:difficult, easy, hard, dangerous, safe, useful, pleasant, interesting, impossible等。 It is impossible for a child to answer the question. 小孩子不可能回答出这个问题。 It is dangerous for you to swim alone. 你自己一个人去游泳很危险。 3. 主语+be动词 +形容词+动词不定式 这一句型常用表示感情、情绪,以及表示能力和意志的形容词, 如: glad, pleased, sorry, sad, thankful 或ready, able, sure, certain等。 I'm very sorry to hear the news.