1．过去分词作定语时，相当于形容词。单个的过去分词常常置于所修饰的名词前；而过去分词短语常常置于所修饰的名词后。
They are cleaning the fallen leaves in the yard.
他们正在打扫院子里的落叶。
The concert given by their friends was a success.
他们朋友举办的音乐会很成功。
2．过去分词及过去分词短语作定语一般可转换为一个定语从句。
We must adapt our regulations to the changed conditions.
＝We must adapt our regulations to the conditions that have been changed.
我们必须调整规章制度来适应变化了的情况。
