现在分词的时态
过去分词没有时态形式的变化，所以这里只讲现在分词的时态形式。
1)现在分词的时态形式
一般式writing
完成式having written
2)现在分词一般式其所表示的动作与谓语动词所表示的动作同时发生，或在谓语动词所表示的动作之前或后发生。如：
Working together with Dr. Bethune，we learnt a lot from him.
我们在和白求恩大夫一起工作期间，向他学到很多东西。
(working与leamt同时发生)
Knowing that they were going abroad next week ，they began to make preparations.他们知道他们下星期要出国，所以都开始作准备。(knowing发生在began之前)
He came up to me，saying"Glad to see you again."他来到我跟前说道，"很高兴又见到你。"(saying发生在came之后)
3)现在分词完成式其所表示的动作发生在谓语动词所表示的动作之前，常常用作状语，表示时间或原因。如：
Having done his homework，the schoolboy began to write his diary.这个小学生做完作业后，开始写日记。(having done his homework发生在began之前，表示时间。)
Not haying done it right, I tried again.没有做对，我就又试。
(not having done发生在 tried之前，表示原因。)
现在分词的被动语态
一般式being written
完成式haring been written
如：
This is one of the many dams being built the river.这是沿河修筑的许多水坝之一。
Being surrounded，the enemy troops were forced to surrender.敌军被包围了，被迫投降。
Having been asked to stay，I couldn't very well leave.人家请我留下，我就不好离开了。
独立结构(absolute construction)
分词短语所表示的动作在逻辑上有主语，这种主语皆可在同一句中找到。如：
The young woman standing over there is our new English teacher.站在那边的年轻妇女是我们新的英语老师。(分词短语standing over there的逻辑主语是 the young woman)
Having finished his work，he went out to play volleyball.他做完工作后，出去打排球。(having finished his work的逻辑主语是he)但有时分词短语有它自己的独立的主语，这种主语常常是名词或代词(主格)，放在分词短语之前，这种结构叫做独立结构。独立结构常用作状语，多用在书面语中。如：
The dark clouds having dispersed，the sun shone again.乌云已散去，太阳又普照大地了。(时间状语)
We shall thresh the wheat，weather permitting.天气好的话，我们就打麦。(条件状语)
Their room was on the first floor，its broad window overlooking the park.他们的房间在二层楼上，房间里的宽大的窗户俯视着公园。(伴随情况状语，the first floor在英国指第二层楼，在美国指第一层，其余可类推。)
We redoubled our efforts，each man working like two.我们加倍努力工作，一人干两人的活。(方式)
Almost all metals are good conductors，silver being the best of all.几乎所有的金属都是良导体，银是最好的导体。(伴随情况)
The meeting over，we all left the room.会议结束以后，我们就都离开了房间。(时间状语，注意over之前省去了being)
This done，we went home.做完此事，我们就回家了。(时间状语)
She gazed，her hands clasped to her breast.她双手*在胸前凝视着。
[注一]有的分词短语可以独立存在，在句中没有逻辑上的主语。它们往往已经变成习惯用语，必须熟记。如：
Generally speaking，this book is not very difficult.总的说来，这本书并不很难。
Judging from what you say，he has done a very good job.从你的话看来，他的工作做得很不错。
Considering that he has been in china for only a year，he speaks Chinese well.考虑到他到中国才一年，他的中国话讲得很不错了。
类似的习惯用语尚有talking of (谈起)，speaking of (谈到)等引导的分词短语。
[注二]英语里还有一种较口语化的"with + 名词或代词宾格 + 分词 (或形容词、介词短语)"结构，也往往作状语用，表示伴随情况。如：
He fell asleep with the lamp burning. 他没有熄灯就睡着了。
She gazed with her hands clasped to her breast.她双手*在胸前凝视着。
上述结构中的分词亦可用形容词或介词短语代替。如：
He sleeps with the windows open even in winter.他即使在冬天也开着窗户睡觉。
A girl carte in with a book in her hand.一位姑娘手里拿着一本书走了进来。(在笔语中，也可说：A girl came in，book in hand.)
