过去分词短语作状语
    非谓语动词是英语语言所特有的语言现象。其中在学习分词的过程中应该明确，在大多数情况下分词只是从句的一种省略形式，目的在于使语言更为简练，尤其在书面语中。所以无论是现在分词、还是过去分词都与从句的主动、被动、时态有着密切的关系。过去分词短语在句中作状语可表示原因、时间、让步、条件、方式或伴随等。例如：
1.Praised by the neighbours, he became the pride of his parents.
受到邻居们的表扬，他成为父母的骄傲。（表示原因）
For personal use only in study and research; not for commercial use
2. Once seen, it can never be forgotten.
一旦它被看见，人们就忘不了。（表示时间）
3.Seen from the top of the castle, the park looks very beautiful. （表示条件）
For personal use only in study and research; not for commercial use
从城堡顶端看，公园十分美丽
4.Though told of the danger, he still risked his life to entered the cave.
虽然被告之有危险，他仍然冒生命危险进山洞。（表示让步）
5.Filled with hopes and fears, he dived deep into the ocean.（表示伴随）
心中充满了希望与恐惧，他跳进了深海里。
在使用过去分词作状语时, 为了体现上下两部分(句子层面)的逻辑关系, 句子中常出现过去分词和连词的连带使用,比如例2和例4那样的结构. 通过众多例句分析, 我们发现过去分词作状语以下几种情形：
一、 句子的主语与作状语用的过去分词之间在逻辑上是被动的关系
例：_______ by the beauty of nature, the girl from London decided to spend another two days on the farm .（2004，辽宁）
A．Attracting      B．Attracted      C. To be attracted    D．Having attracted
分析：答案为B。句子的主语与作状语用的过去分词之间在逻辑上是被动的关系。可以把状语部分转换为: （As the girl was ）attracted by the beauty of the nature,… attracted 表示被动意义“被迷住，被吸引”。
If they are applied in agriculture, the machines will save farmers much labor.
=If applied in agriculture, the machines will save farmers much labor.
如果将这些机器用于农业，就可以省去农民很多劳动。注：连词if，通常保留。
二、由一些含be动词的短语或系表结构转换来的。这时，句子的主语与作状语用的过去分词之间在逻辑上并没有被动的关系。学过的能够用于这种结构的常见短语有:
be interested in ，
be disappointed at/in/with，
be pleased with，
be astonished\ shocked at，
be embarrassed about,
be confused\ puzzled about
be frightened\ terrified of，
be scared\ horrified of，
be experienced at
be engaged in，
be occupied with，
be involved in，
be addicted to，
be accustomed to，
be adapted\adjusted to，
be used to
be related to
be connected to\ with
be linked to
be associated with
be concerned with，
be stuck\caught(up)\trapped in
be covered with
be filled with
be surrounded with\by，
be faced (up)with
be equipped with， 
be determined to do sth
be devoted\ committed to
be armed with
be furnished with
be seated in
be dressed (up) in
be concerned about
be based on
be buried in，
be bent on，
be focused on ，
be concentrated on，
be prepared with ，
be satisfied with
be upset about
be well-known as\for\to
be designed for
study的过去分词
be meant\intended for
be convinced of
be sentenced to
be amazed\ surprised at
be disappointed with
be lost in
be located in
be charged with
be absorbed in
be attached to
be ashamed of
be mistaken about
be compared with
……
例：________ in a white uniform, he looks more like a cook than a doctor.（2005，湖南）
  A. Dressed      B. To dress      C. Dressing    D. Having dressed     
分析：答案为A。可以把状语部分转换为：When ( he was ) dressed in a white uniform,…作状语的过去分词dressed来自于“be dressed in” 这个短语。be dressed in 表穿着的状态，如：She is dressed in a blue skirt. 句子的主语he与作状语用的过去分词dressed之间在逻辑上并没有被动的关系。
例：________ in the mountains for a week, the two students were finally saved by the local police（2005，江苏）
A. Having lost    B. Lost      C. Being lost    D. Losing
分析：答案为B。可以把状语部分转换为: (After the two students were) lost in the mountains for a week,…. 作状语的过去分词lost来自于“be lost in”迷路，迷失。如：He was lost in the forest. 句子的主语the two students 与作状语用的过去分词lost之间在逻辑
上并没有被动的关系。
三、分词短语由“while/when/unless/if/once /though/although+ 过去分词”构成。它们都可以转换成由“while/when/unless/if/once /though/although + 主语 + 谓语 + 过去分词”结构，这样，整个句子就变成了状语从句。句子的主语与作状语用的过去分词之间在逻辑上是被动的关系。近年来高考题单项填空题中多次考查了这种用法，值得我们复习时注意。
例：The research is so designed that once______ nothing can be done to change it. (2002,广东)
A. begins  　B. having begun      C. beginning    D. begun
分析：答案为D。可以把此句转换为状语从句：The research is so designed that once (it is )begun nothing can be done to change it.
例：Unless______ to speak, you should remain silent at the conference. (2003,上海春招)
A. invited      B. inviting    C. being invited  D. having invited
分析：答案为A。可以把状语部分转换为：Unless (you are) invited to speak,…
例：Generally speaking, ______ according to directions, the drug has no side-effect. (2003上海)
A. when taking  　B. when taken  　C. when to take  D. when to be taken
分析：答案为B。同样可以把状语部分转换为：…when (the drug is )taken according to directions,…
你能给出下边高考题的正确答案并说明理由吗？
1. It shames me to say it, but I told a lie when ________ at the meeting by my boss.
A. questioning    B. having questioned  C. questioned  D. to be questioned
2. When first ________ to the market, these products enjoyed great success.(2004,全国II)
A. introducing  B. introduced  C. introduce  D. being introduced
3.When _______ help, one often says“Thank you.”or“It’s kind of you.”（2005，福建）
A．offering    B．to offer      C．to be offered      D. offered
4. When_____, the museum will he open to the public next year. (2002,上海春招)
A. completed  　B. completing  C. being completed  D. to be completed
答案：1. C (= when a lie is questioned)
2. B (=When these products were introduced) 
3. D (=When one is offered to help) 
4. A (=When the museum is completed)
四：分词短语中的动词的动作发出者不是后面句子的主语发出的，其逻辑主语同句子的主语也不一致， “主语+过去分词短语” 即独立主格结构。
    作状语用的分词，其逻辑主语必须同句中主语为同一人或同一事，如以上所举的各例。
但英语中有一种语法现象，那就是当分词有它自己的独立主语（不同于句子主语的名词或代词）时，则是一种独立主格结构形式，在句中作状语等。
The test finished, we began our holiday.  = When the test was finished, we began our holiday.