被动语态复习
语态(voice)，作为一个语法范畴，是表示主语和动词之间的主动或被动关系的动词行式。英语动词有两种语态：主动语态(active voice)和被动语态(passive voice)。当主语为动作执行者即施动者时，动词用主动态；如果主语是动作的承受者即受动者时，动词便用被动态。例如：
(1) john helped peter.
(2) peter was helped by john.
句(1) helped是主动态；句(2)was helped是被动态,可见主动态是无标记的，而被动态是有标记的。
构成
被动语态由助动词be的时态之一和及物动词的过去分词构成。被动语态可用于各种时态，其时态变化通过助动词be的不同形式来体现。如：一般现在时的被动态构成形式为助动词am/is/are + 过去分词；而一般过去时的被动态构成形式为was/were + 过去分词。本册要掌握的被动语态形式有：
一般现在时：am/is/are + 过去分词
e.g. football is played all over the world.
i’m often asked to do this work.
我常常被派做这项工作。
一般过去时：was/were +过去分词
e.g. the terracotta warriors were found in 1974 near xi’an.
they were discovered by workers in a field outside the city.
when was the building completed?
这座大楼什么时候建成的？
一般将来时：will (shall) + be +过去分词
be going to + be + 过去分词
e.g. the result of the exam will be known soon.
they are going to be given a difficult test.
一般过去将来时：should(would) be+过去分词
e.g. the teacher said the results would be published soon.
he told me that the film would be shown the next week.
现在进行时：am/is/are + being +过去分词
e.g. the new airport is being built by a foreign company.
一家外国公司正在承建这座新机场。
the song is being sung by the girls now.
过去进行时：was/were being+过去分词
e.g. the song was being sung by the girls when i got there.
the student was being criticized when i went into the
teacher’s office.
将来完成时：will have been+过去分词
e.g. by the end of next term english words will
have been learned.
the building will have been built by next year.
现在完成时：has/have + bee n +过去分词
e.g. all the tickets have been sold .
the book has been translated into many languages.
这本书已被译成多种语言。
过去完成时：had been+过去分词
e.g. forty schools had been visited by last year.
all the tickets had been sold out when i got to the cinema.
过去将来完成时：would have been+过去分词
e.g. he said many words would have been learned by .
they promised that ten books would have been published
by the next month.
情态动词：情态动词 + be + 过去分词
e.g. this road must be mended.
the machine parts may be needed in our work.
