过去分词作状语
过去分词短语作状语，可表示时间，原因，条件等，可发展为一个状语从句。过去分词作状语时其逻辑主语为主句的主语。
过去分词作状语时的具体用法：
1. 过去分词作时间状语相当于一个时间状语从句。例如：
Asked (When he was asked) what had happened, he lowered his head.
当他被问问题的时候,他低下了头。
2. 过去分词作原因状语相当于一个原因状语从句。例如：
Frightened (=Because / As she was frightened) by the tiger, the girl didn’t dare to sleep alone.
因为害怕老虎, 这个女孩不敢单独睡觉。
3. 过去分词作条件状语相当于一个条件状语从句。例如：
Grown (If these seeds are grown) in rich soil, these seeds can grow fast.
如果种在肥沃的土壤里， 这些种子能长得很快。
4. 过去分词作让步状语相当于一个让步状语从句。例如：
Left (Although he was left) at home, John didn’t feel afraid at all.
虽然John被单独留在房间里, 他一点都不害怕。
5. 过去分词作状语表示伴随动作或状态。例如：
The teacher entered the classroom, (and he was) followed by a group of students.
老师进入教室，后面跟着一帮学生。