Unit 3 Fascinating Parks动词ing 形式作主语一、关于动词ing 形式的基本情况1．动词ing 形式是动词的一种非谓语形式，包括现在分词和动名词两种。动词ing 形式在句中的语法作用：动名词在句中作主语、宾语、表语和定语，现在分词在句中作状语、宾语补足语和定语。2．动词ing 形式的时态和语态。【观察例句】Reading aloud is a good way to learn a language.大声朗读是学习语言的一种好方法。Having studied his lessons very hard, he passed the exam.努力学习了功课, 他通过了考试。The building being built now will be finished next month.正在建设的建筑物下个月将完工。Having been laughed at for his lameness, the boy became shy and inhibited. 那男孩因跛脚被人讥笑, 变得羞怯。【归纳用法】语态时态 主动语态被动语态一般式doingbeing done完成式having donehaving been done二、动词ing 形式作主语1．动词ing 形式作主语【观察例句】Saying is one thing, and doing is another.说是一回事，而做是另一回事。Having a walk every day helps to make one keep healthy.每天散步有助于一个人保持健康。【归纳用法】动词ing 形式作主语，往往表示经常性、习惯性的动作，通常置于句首。[名师点津]动名词作主语时，谓语动词用单数。Climbing mountains is really difficult for the old.对于老人来说爬山确实困难。2．形式主语 it 代替动词ing 形式作主语。【观察例句】It is a waste of time persuading such a person to join us.劝说这种人加入我们是浪费时间。It is no good/use regretting for the past.悔恨过去是没用的。It's useless arguing with them. 跟他们争论是徒劳无益的。【归纳用法】此类句式常见的有：It's a waste of time doing sth.做某事是浪费时间It's useless/worthwhile doing sth.做某事没用/是值得的It's no good/use/fun doing sth.做某事没好处/没用/没意思3．动词ing 形式和 to do 作主语时的区别。【观察例句】Playing with fire is dangerous.玩火危险。(泛指)Singing is my hobby, and to sing at my friend's birthday party is my dream.唱歌是我的爱好，在朋友的生日宴会上唱歌是我的梦想。【归纳用法】动词ing 形式和 to do 都可以作...
