1.单个过去分词
（1）作定语时一般置于被修饰词之前。
We need more qualified teachers.我们需要更多合格的教师。
We will meet at a given time.我们将在指定的时间见面。
This is a used cellphone.这是一部旧手机。
（2）left表示“剩下的”作定语时也可后置。
The book left are for my students.剩余的书是给我学生的。
There is no more time left.没有时间了。
（3）only，very，the first，the last等词修饰名词时，过去分词作定语要后置。
That is the very thing wanted.那正是所需要的东西。
This is the only machine required.这是唯一需要的机器。
（4）修饰复合代词或指示代词those时，过去分词作定语要后置。
Is there anything unsolved？ 还有没有未解决的问题？
She is one of those invited.她是那些被邀请的人之一。
2.过去分词短语
（1）过去分词短语作定语时要后置。
He is a teacher respected by the students.他是一个受学生尊敬的老师。
The bridge built last month needs repairing.上个月建造的那座桥需要修理。
（2）过去分词作定语时相当于定语从句。
This will be the best novel of its kind ever written.
this will be the best novel of its kind that has ever been written.
这将是这类小说中写得最好的。
Most of the people invited to the party were my old friends.
most of the people who had been invited to the party were my old friends.
大多数被邀请参加聚会的人都是我的老朋友。