sit
1.sit down是一时的动作。例如：He sat down by the fire and soon went to sleep. 不可说He sat down by the fire for nearly three hours，该把down删去。
2.There were two birds sitting on the branch里的sitting是“停”，不是“坐”，实际是standing。
3.下面两句意思不同：
- He sat reading all the morning. （他整个上午坐着阅读［不是坐着写字或画图］。）
- He read sitting all the morning. （他整个上午坐着阅读［不是站着或躺着阅读］。）
下面两句里的teach sitting和cook sitting不可改作sit teaching和sit cooking：
- He had to teach sitting because he had a sore foot.
- She says she can't cook sitting.
参见stand 3和lie 2
4.下面两句都作“他将参加这次考试”解，似乎近几年来才有省去for的：
- He is going to sit for the examination.
- He is going to sit the examination.
