关于高中英语的一些问题

Question

我想问问动词放在句首的时候什么时候用ed ing 或者不定式之类的?把可以的情况告诉下我好吗.举些例句 谢谢

Answer 1

加ed作句首：动词与主语之间是被动关系。Caught by the police, the thief had to give up.
加ing 作句首，1.动词与主语之间是主动关系，doing 形式做状语。Singing and dancing, the children celebrated happily.
2，doing 形式做主语。Reading in bed is bad for your eyes.
to do 作句首，1. 表目的，做状语。To help the poor, he donated all his saving.
2. 做主语。 To help the poor is his job.

Answer 2

主要看后面的主语， 主语与动词是被动关系用ed，与动词是主动关系用ing 不定式作主语表目的，有时不定式加动词短语作主语就相当于一个名词。
Doing homework late, he was punished.
Exposed to sunslight, the followers are growing healthily.
To help others is the duty of teenagers.
To watch the football game on TV, he went home early.