分词作状语
分词作状语实际把状语从句简化。简化的条件：其逻辑主语一定要与主句的主语保持一致。
While he was reading the book, he nodded from time to time.
----Reading the book, he nodded from time to time.
Because he was shy, he didn’t come to the party.
----Being shy, he didn’t come to the party.
As the book is written in simple English, the book is easy to read.
----Written in simple English, the book is easy to read.
2. 分词作状语时可分为以下几种形式：
* doing ： 用来表示主动，且前后动作同时进行。
Returning home later, my friend learned that the police had been to the flat.
* having done: 用来表示主动,且动作发生在主句之前。
Having seen the film before, I decided not to see it again.
* being done: 用来表示被动,且前后动作同时进行。
Being questioned by the police, he felt frightened.
* done: 用来表示被动且完成
Destroyed in the storm, the house will be rebuilt.
* having been done: 用来表示被动，而且强调动作持续 一段时间或次数。
Having been defeated three times, he had to give up.
* 否定形式： not/ never + 分词结构
Not studying hard, he didn’t pass the test.
Never having taken a plane before, he was nervous.
3. 分词作状语如果前后主语一致可简化时间、条件、原因、结果和伴随等状语从句。
(条件)
If you work harder, you will do better in the exam next time.
---- Working hard, you will do better in the exam next time.
（时间）
After I did my homework, I went back home.
----Having done my homework, I went back home.
(伴随）
He hurried to the station and hoped to catch the last train.
---- He hurried to the station, hoping to catch the last train.。
(原因)
Because my friend was frightened of losing his job, he said nothing to the police.
----Frightened of losing his job, my friend said nothing to the police.
(结果)
His parents were killed in the SARS epidemic and left him an orphan.
---- His parents were killed in the SARS epidemic, leaving him an orphan.
