介词 + -ing

介词（in、on、at、of、for、about、with、without、by、before、after、instead of…）后面接名词。如果介词后面直接跟动词，这个动词必须用 -ing 形式（动名词）——不能用原形，也不能用 to + 动词。

💡中文里“之前”“通过”后面的动词不变形（“出门之前”“通过坐公交”）。英语不一样：紧跟在介词后面的动词必须加 -ing。只要看到 before、after、by、without、instead of、for、about… 后面跟着动词，就检查一下有没有用 -ing。

1. By + -ing——做某事的方式，或得到结果的方法

• You can save a lot of money by cooking at home.

  在家做饭可以省下很多钱。

• She improved her English by watching films with English subtitles.

  她通过看带英文字幕的电影提高了英语。

2. Without + -ing——本以为会发生的事没有发生

• He left the party without saying goodbye.

  他没说再见就离开了聚会。

• Don't go out without locking the door.

  出门别忘了锁门。

3. Before / after + -ing——一个动作在另一个动作之前或之后

• Wash your hands before eating.

  饭前要洗手。

• After finishing university, Minh moved to Da Nang.

  大学毕业后，阿明搬到了岘港。

• Before leaving, please turn off the lights.

  离开前请关灯。（不说：Before to leave）

4. Instead of + -ing——做一件事来代替另一件事

• Instead of taking a taxi, we walked home.

  我们没打车，而是走回了家。

• Why don't you call her instead of sending a message?

  你为什么不给她打个电话，而是发消息呢？

5. Thanks for / sorry for + -ing——为做过的事道谢或道歉

• Thanks for helping me with the move.

  谢谢你帮我搬家。

• Sorry for not replying sooner — I was busy with exams.

  抱歉没早点回复——我忙着考试。（否定：not + -ing）

6. How about / what about + -ing——提出建议

• How about having a picnic this weekend?

  这个周末去野餐怎么样？

很多形容词、动词和名词都有固定搭配的介词（见“形容词 + 介词”和“动词 + 介词”两课）。如果后面接的是动作，这个动词也要用 -ing。

• My dad is really good at cooking Vietnamese food.

  我爸爸很会做越南菜。

• Phong is thinking about moving to Da Nang.

  阿峰在考虑搬到岘港。

• Did they succeed in finding a flat?

  他们找到房子了吗？（不说：succeed to find）

• I love the idea of living in the countryside.

  我很喜欢住在乡下这个想法。

可以在 -ing 前面加上一个人，表示谁做这个动作：I'm tired of people telling me what to do. We're worried about him driving at night.

通常 to 后面接动词原形（want to go）。但在一些短语里 to 是介词，所以后面接名词或 -ing：look forward to、be/get used to、object to、prefer … to …、when it comes to、in addition to。

• We're really looking forward to seeing you.

  我们非常期待见到你。（不说：to see）

• I prefer walking to driving in the city.

  在城里我宁愿走路也不愿开车。

• When it comes to cooking, my brother is the expert.

  说到做饭，我哥哥可是行家。

💡检验方法：在 “to” 后面放一个名词。如果句子仍然成立（I'm looking forward to the holiday），“to” 就是介词 → 用 -ing。如果不成立（I want to the holiday——错），就用动词原形。另见“‘be used to’ + -ing”一课。

• 否定：把 not 放在 -ing 前面——Sorry for not calling. / She got sick by not eating properly.
• 被动：being + 过去分词——He got into the building without being seen. / I hate the idea of being watched.
• 表示更早发生的动作，可以用 having + 过去分词，但一般用普通的 -ing 就足够清楚：He was proud of winning / of having won the prize.
• -ing 隐含的主语就是主句的主语：After finishing lunch, we went back to work（吃完午饭的是我们）。避免说 After finishing lunch, the meeting started——听起来像是会议吃了午饭。
• before / after 也是连词，所以也可以接完整的从句：Before I left, I called my mum. = Before leaving, I called my mum. 两部分主语相同时，用 -ing 更简洁。

• ✗I'm interested in learn Korean.

  ✓I'm interested in learning Korean.

  介词 in 后面的动词要用 -ing。

• ✗Before to leave, please turn off the lights.

  ✓Before leaving, please turn off the lights.

  before 是介词，后面不接 to + 动词。

• ✗Thanks for help me.

  ✓Thanks for helping me.

  for 是介词 → helping。

• ✗He's thinking about to buy a car.

  ✓He's thinking about buying a car.

  介词 + -ing，不接 to + 动词。

• ✗She's good in drawing.

  ✓She's good at drawing.

  good 后面的介词是 at。

• ✗He left without say anything.

  ✓He left without saying anything.

  without + -ing。