过去分词作定语可以位于名词之前或名词之后。
1. 位于名词之前的过去分词定语一般只有单个词。
The new product finally passed the required test. 新产品终于通过了要求的测试。
Those repeated efforts were still inadequate. 这些重复的努力仍然不足。
过去分词之前还可以有副词修饰，如：
The prime minister issued a cautiously worded statement this afternoon. 今天下午首相发表了一份措辞谨慎的声明。
There are many beautifully decorated houses in this rich area. 这个富人区有许多装饰精美的房子。
有些过去分词已演化为形容词，如：excited (兴奋的), worried (担忧的), crowded (拥挤的), retired (退休的), escaped (逃脱的), used (用过的，二手的)。
2. 如果是过去分词短语或结构，则放在名词后作后置定语。
The idea presented by Peter is much simpler. 彼得提出的想法要简单得多。
It is a house built by the Romans. 它是一栋古罗马人建的房屋。
The man followed by security guards is our chairman. 保安人员跟着的那个人是我们的主席。
单个过去分词也是可以作后置定语的，如：
The experience gained will give you more confidence to help your customers. 获得的经验会给你更多的信心去帮助你的客户。
过去分词短语后置定语的作用相当于定语从句，如：
The meeting held yesterday is of great importance. = The meeting which was held yesterday is of great importance. (昨天举行的会议非常重要。)
3. 过去分词多数情况下由及物动词充当，含有被动或动作完成的意义，如下边的及物动词 need。
All the tools needed will be fully supplied. 所需的所有工具将全部供应。
这种情况下，被修饰的名词在逻辑上相当于被动句中的主语，如： a broken cup = the cup is broken。
4. 过去分词也可以由不及物动词充当。这种情况下的过去分词没有被动意义，只表示动作的完成状态，如:
The risen sun is so bright. 升起的太阳如此耀眼。
The chairman was dismissed because of fallen profit. 董事长因利润下降而被解雇。
