动名词（动词-ing 形式）具有名词性质，可作主语和宾语。
要点讲解
- 作主语（谓语用单数）：Reading is my hobby. 阅读是我的爱好。
- 作主语时可用 it 作形式主语：It's no use crying. 哭没有用。
- 作宾语（动词后）：enjoy doing, finish doing, practice doing, mind doing, keep doing, avoid doing, suggest doing, consider doing。
- 作介词宾语：be good at doing, be interested in doing, thank you for doing, look forward to doing。
- 固定句型：spend time（in）doing 花时间做某事；have fun doing 做某事很开心；be busy doing 忙于做某事。
- 动名词作主语与不定式作主语的区别：动名词表示一般性、习惯性动作；不定式表示具体的、一次性的动作。
- 动名词的逻辑主语：my/your/his + doing：Do you mind my opening the window? 你介意我开窗吗？
经典例句
- Swimming is good for our health.
游泳对我们的健康有好处。 - He finished doing his homework at nine.
他九点完成了作业。 - She is good at singing English songs.
她擅长唱英文歌。
易错提醒
- enjoy/finish/practice/mind/keep/suggest 后必须接动词-ing，不能接 to do——这是固定规则。