动词的时态
在英语中,由于谓语动作发生的时间不同,或表达不同时间存在的状态,谓语动词都要发生相应的变化.这些动词的形式就叫做动词的时态.
英语动词的时态共有16种,列表如下:(以动词write为例)
被动语态的构成
被动语态由助动词be加过去分词构成,时态通过be表现出来.构成被动语态的一般疑问句时,须将第一个助动词移至主语之前,构成被动语态的否定句时,助动词后须加not. 各个时态的被动形式列表如下:(以动词teach为例)
英语被动语态讲解
（一）语态的基本概念和种类
语态是动词的一种形式，用来表明主语与谓语动词之间的关系。所以英语的语态是通过动词形式的变化表现出来的。语态有两种：主动语态和被动语态。主语是动作的发出者为主动语态；主语是动作的接受者为被动语态。
如：They built the bridge.
The bridge was built by them.
(二)被动语态的构成
被动语态由“助动词be＋及物动词的过去分词”构成。人称、数和时态的变化是通过be的变化表现出来的。
歌诀是：被动语态be字变，过去分词跟后面。
情态动词的被动语态是常考的一个知识点：情态动词+be+过去分词
(三)被动语态的用法
1)不知道或没有必要说明动作的执行者是谁。例如：
Some new computers were stolen last night. 一些新电脑在昨晚被盗了。(不知道电脑是谁偷的)
This book was published in 1981. 这本书出版于1981年。
(2)强调动作的承受者，而不强调动作的执行者。例如：
the window was broken by Mike. 窗户是迈克打破的。
This book was written by him. 这本书是他写的。
Eight hours per day for sleep must be guaranteed. 每天8小时睡眠必须得到保证。
（四）主动语态变被动语态的方法与注意事项
(1) 通常的办法是：将主动结构中的宾语变为被动结构中的主语，将主动结构中的谓语动词变为“be / get +过去分词”形式，将主动结构中的主语变为介词by的宾语(若动作的执行者没有必要说明则可以省略该by短语)。如：
Li Lei planted t he tree last year. → The tree was planted by Li Lei last year. 这棵树是李蕾去年栽的。
Workers made the machines in Changsha. → The machines were made in Changsha.
这些机器是长沙造的。
(2) 将含有复合宾语的句子变为被动语态时，应将宾语变为被动结构的主语，而宾语的补足语则留在原处成为主语补足语。如：
He painted the door green yesterda y. →The door was painted green yesterday. 昨天门被漆成绿色了。
注意：表示“使、让”的动词make, have等，以及感官动词see, watch, observe, feel, hear, listen to, look at等，在主动语态中，接不定式做宾语补足语时，不定式前的to 要省略，而变为被动语态时，成为主语补足语的不定式，则必须带to。如：
I saw him go into the teachers’ office. →He was seen to go into the teachers’ office.
看见他进入了教师办公室。
(3) 带双宾语的句子变为被动语态时，既可将直接宾语变为被动语态的主语，而在间接宾语前加to 或for留在动词之后；也可将间接宾语变为被动结构的主语，而直接宾语留在动词之后。但一般采用后一种用法。如：
He gave me the pen last year. →I was given the pen last year. / The pen was given to me last year. 这支笔是去年给我的。
【说明】一般说来，间接宾语前带to的动词有：bring, give, hand, lend, offer, pass, post, send, show, take, teach, tell, write, throw等；间接宾语前带for的动词有：book, buy, call, cook, do, get, make, save等。
(4) 动词believe, consider, declare, expect, know, report, say, suppose, think等的被动语态，常有两种结构形式。如：
He was said to get hurt in the car accident. 人们说他在车祸中受伤了。
It was said that he got hurt in the car accident. 人们说他在车祸中受伤了。
(5) 短语动词变被动语态时，短语动词后面的介词或副词不能省略。如：
She has never been operated on before. 她从未动过手术。
The baby was looked after by her sister. 这婴儿由她的姐姐照顾。
His plan was laughed at by everyone. 他的计划大家都嘲笑。
（6）动词不定式的被动语态：即把to do 变成to be done
（五）不用被动语态的情况
1) 不及物动词或动词短语无被动语态：
appear, die, disappear, end , fail, happen, last, lie, remain, sit, spread, stand ,break out, come true, fall asleep, keep silence, lose heart, take place.
After the fire, very little remained of my house.
比较：rise, fall, happen是不及物动词；raise, seat是及物动词。
(错) The price has been risen.
(对) The price has risen.
(错) The accident was happened last week.
(对) The accident happened last week.
(错) The price has raised.
(对) The price has been raised.
