新概念英语第二册第48课课文重难点 Further notes on the text 1Dentists always ask questions when it is impossible for you to answer. 牙科医生们总是在你无法作出回答的时候向你提出问题。在when引导的时间状语从句中，it为先行主语，代指后面的不定式，for+人称代词名词说明不定式表示的动作是谁做的：It is not hard for you to help them.你帮助他们并不难。It was a mistake for me to come to the party.我来参加晚会是错误的。impossible通常不以人作主语，而以不定式或从句作主语：It is impossible for him to help you.他不可能帮你。It is impossible that he will help you.（译文同上）2In answer to these questions I eith
