最好举例说明,有些不大懂.

最好举例说明,有些不大懂.
最好举例说明,有些不大懂.

最好举例说明,有些不大懂.
一、虽然过去分词与现在分词一般被动式都有被动意义,但是过去分词只强调被动意思,表明动作已经完成,而现在分词一般被动式既有进行又有被动的意味.在下列各种用法中区别非常明显：
(1)过去分词在构成完成时态,不定式完成式以及被动语态时,通常不能用现在分词一般被动式代替.(现在进行时的被动语态除外)
eg：The door was closed an hour ago．
这门在一小时前就关闭了.
They have finished their homework.
他们已经做完了家庭作业
(2)过去分词作前置定语时,不能用现在分词一般被动式代替.
eg：That was an inspired suggestion．
那是一条由某人提出的建议.
同样现在分词一般被动式作为定语表示动作时,也不能用过去分词来代替.
eg：The house being built is a big project.
正在施工的那幢楼是一项大的工程.
(3)过去分词作条件、时间等状语时,不可用现在分词一般被动式代替.
eg：Given more time,I can do it better．(表条件)
多给点时间,我会做得更好些.
Given more attention,the trees could have grown better.(MET 90)(表示条件)
如果多关心一些,这些树会长得更好.
Heated ,the metal expands．(表示时间)
加热后,这种金属会膨胀.
Asked why he did it,he said it was his duty ．(表示时间)
问及为何要做此事时,他说这是他的职责.
(4)过去分词作表语时,不能用现在分词一般被动式代替.
eg：The top of the mountain is covered with snow .山顶满是雪.
(5)过去分词在构成have,get,want等动词后的复合宾语时,不能用现在分词一般被动式.
eg：Why don’t you have the radio fixed?
你为什么不把收音机拿去修一修?
尤其是一些感官动词,如：see,hear,find等后构成复合宾语时,过去分词和现在分词一般被动式意思完全不同.
eg:I heard this song being sung by my students in the next room.
我听到隔壁房间的学生正在吟唱这首歌.
(注：现在分词一般被动式表示正在进行的动作)
I have never heard this song sung in English．
我从来没有听到过用英语唱这首歌.
(注：过去分词表示己完成的动作)
(6)在下面一些比较固定的分词独立结构中,通常多用过去分词.
eg:all told总计
all things considered考虑了一切因素之后
this accomplished完成这项工程之后
this explantion given这样解释之后
all said and done毕竟
二．过去分词和现在分词完成被动式的区别：
及物动词的过去分词没有完成式,但它有“完成”的含义,所以它可以代替现在分词完成被动式.
eg:The bridge had been weakened by successive storms and was no longer safe .=
Weakened by successive storms,the bridge was no longer safe.=
Having been weakened by successive storms,the bridge was no longer safe.=
这座桥接二连三地遭到暴风雨的袭击后,己经不安全了.
但若强调分词表示的行为发生在后一个动词表示的行为之前时,可用现在分词完成被动式.
eg:Having been warned about the bandits,he left his valuables at home.
当警告有强盗出没时,他就把贵重物品留在家里.
通常过去分词可作定语使用,而现在分词完成被动式却不能用作定语.
eg:The computer centre,opened last year,is very popular among the students in this school.(MET 93)
去年开办的计算机中心很受学生的欢迎.
(过去分词既能表示被动又有完成的含义)
The first textbooks written for teaching English as a foreign language came out in the 16th century.(NMET 94)
作为外语的英语教科书早在十六世纪就已经出版了.
Most of the artists invited to the party were from south America(MET 90)
应邀参加舞会的大多数艺术家都来自南美.
过去分词可以用“连词＋过去分词”的结构作状语,其实质就是状语从句的省略,而现在分词的完成被动式却不能这样用.
eg:Once seen,it can never be forgetten.
目睹一眼,终生难忘.
If bitten by a snake,you should send for help and don't walk
要是你被蛇咬了,你应当向别人求助而不要走.
When shot in the leg,he continued to fire back with his gun.
虽腿部己遭枪击,他人仍然继续开枪还击.
The room,although supposed to be kept locked,was often left open.
通常以为是锁着的那个房间,其实经常敞开着.
综上所述,过去分词与现在分词被动式无论其形式和内涵,都有一定的差异.正确地区别它们的异同,准确地运用它们的表达形式,对英语学习者来说,尤为重要,只要多加比较,反复体会,就能掌握这一知识点.