过去分词是什么？如何构成过去分词？
过去分词（Past Participle）是一种非谓语动词形式，通常由动词的过去分词形式构成。过去分词可以用作形容词，描述被动、完成、状态等。过去分词的构成方式因动词不同而有所不同。规则动词通常在动词原形后加上 “-ed”，而不规则动词则有不同的过去分词形式。
例如：
- 规则动词：”play” → “played”、”walk” → “walked”
- 不规则动词：”go” → “gone”、”write” → “written”
在句子中，过去分词可以用于不同的作用：
- 作为形容词：
- The broken window needs to be fixed.（破碎的窗户需要修理。）
- 作为被动语态的一部分：
- The book was written by a famous author.（这本书是由一位著名作者写的。）
- 作为完成时态的一部分：
- She has already eaten dinner.（她已经吃过晚饭了。）
过去分词通常用作形容词或与助动词连用来构成各种时态和语态。不同动词的过去分词形式有很多变化，所以需要逐个学习并记忆。
过去分词独立结构
过去分词可以在其前用名词或代词来表明动作的执行者，即过去分词的逻辑主语。 这种名（代）词加上过去分词的结构称为独立主格。 它在句中作状语，表示条件、原因，伴随动作或方式等。
* The duty completed, he had three months’ leave. 任务完成后，他休了三个星期的假。
* Everything considered, it is possible for us to get there in time. 一切因素考虑在内，我们及时到达那里是可能的。
过去分词的用法
1) 和have一起构成完成时态或构成非谓语动词的完成形式。
* My mother has taught English for twenty years. 我妈妈教英语教了20年。
* When I got to the airport, the plane had taken off. 我到达机场的时候，飞机已经起飞了。
* The house was to have been ready today. 这房子本该今天竣工的。
* Having suffered such heavy pollution already, it may now be too late to clean up the river. 这条河已经受到很严重的污染了，现在才来清理可能太晚了。
2) 构成被动语态或非谓语动词的被动形式。
* My homework has been finished. 我的作业完成了。
* They were sentenced to death. 他们被判了死刑。
* The room is being built. 房间正在建设当中。
* He was said to have been arrested. 据说他被捕了。
* These are the problems to be discussed at the next meeting. 这是下次会议要讨论的问题。
3) 作表语
* Please remain seated. 请不要站起来。
* He seemed embarrassed. 他似乎很尴尬。
* The question still remains unsettled. 问题仍未解决。
4) 作定语
a) 前置定语
* The injured workers are now being taken good care of in the hospital. 受伤的工人现正在医院受到良好的照料。
* They are cleaning the fallen leaves in the yard. 他们正在打扫院子里的落叶。
b) 后置定语
过去分词短语或单个的过去分词可以作后置定语
* Is there anything planned for tomorrow? 明天有什么活动吗？
* The suggestion made by the foreign expert was adopted by the manager. 外国专家提出的建议被经理采纳了。
* This is a letter written in blue ink. 这是一封用蓝墨水写的信。
* Is there anything unsolved? 有什么问题没解决的吗？
* The persons involved were all killed by an unknown killer. 牵涉其中的人都被神秘杀手杀死了。
3) 作复合宾语
a) 动词 + 名(代)词 + 过去分词
* I must get my bike repaired. 我必须要修理我的自行车了。
* He was trying to make himself understood. 他正在努力使人们明白他的意思。
* When will you go to the hospital and have your tooth examined? 你什么时候去医院检查你的牙齿？
* I want the plan carried out next year. 我希望明年可以执行这计划。
* Please keep us informed of the latest development. 请随时让我们知道最近的发展动态。
b) 介词 with + 名(代)词 + 过去分词
* The girl sat there with her hand tied back. 这个女孩坐在那里，双手被捆绑在后面。
* With the homework finished, he was allowed to watch the football match. 完成作业之后，他被允许看足球赛。
4) 作状语
a) 过去分词作状语可位于句首，句末或插入在句子中。
* Given more time, we could do it much better. 多给点时间，我们会做得更好些。
* The professor came in, followed by a group of young people. 教授走进来，后面跟着一群年轻人。
* Mr. Green, deeply moved, thanked us again and again. 格林先生深为感动，一再向我们致谢。
b) 有时单独一个过去分词也可作状语
* Heated, water changes into steam. 水加热时就会变成水蒸气。
* She turned away disappointed. 她走了，心里很失望。
c) 过去分词可与连词连用作状语。
* Once published, this dictionary will be very popular. 一旦出版，这本字典将会很受欢迎。
* When asked why he came here, the boy kept silent. 当问及为什么来这里时，男孩就保持沉默了。
* Jane is a shy girl and she never speaks until spoken to. 简是个害羞的女孩，别人开口和她说话之前，她从不说话。
* Although published many times, the book still sells well in the market.
