在英语语法中，一些介词后需要加动词ing形式，如感官动词（如see, hear, feel, watch）、动词后接介词（如admit, avoid, enjoy, suggest）以及介词短语（如in spite of, instead of, look forward to, be good at）。这是一个常见的语法规则，需要在学习英语的过程中注意。
1. 感官动词
以下介词后面需要加动词ing形式，表示感官的动作：
- see: I saw him running in the park.
- hear: She heard me singing in the shower.
- feel: I feel the rain falling on my skin.
- watch: We watched them playing soccer.
2. 动词后接介词
以下动词后面需要接介词，而该介词后面需要加动词ing形式：
- admit: He admitted to stealing the money.
- avoid: I avoid going to crowded places.
- enjoy: We enjoy walking in the park.
- suggest: She suggested going to the beach.
3. 介词短语
以下是一些常见的介词短语，需要加动词ing形式：
- in spite of: In spite of feeling tired, she continued working.
- instead of: I decided to go for a walk instead of watching TV.
- look forward to: I am looking forward to seeing you again.
- be good at: She is good at singing and dancing.
英语知识