被動語態復習
工作中可能需要這些機器零部件。
動詞不定式：to be + 過去分詞
e.g. i’m glad to be asked questions.
it is impossible for lost time to be made up.
失去的時間不可彌補。
主要用法
被動態常用于下列幾種場合：
1.當不知道或不必提出動作的執行者時（這時都不帶由by引起的短語）；
printing was introduced into europe from china.
印刷術是從中國引入歐洲的。
the airplane was made in u.s.
such books are written for children. 這種書是為兒童寫的。
2. 動作的承受者是談話的中心（這時可帶有由by引起的短語）；
the song was composed by a student.
這首歌曲是一個學生譜寫的。
thousands of rivers are polluted in the country.
3. 出于禮貌措詞等原因而不愿說出動作執行者是誰。
you are requested to get here in time.
請您準時來這兒。
帶行為主體的被動態
行為主體就是動作的執行者，即執行動詞所表達的動作的人或物。在被動句中，往往不提及行為主體；但當強調動作的執行者時，可用介詞by引出行為( by +主體行為主體),置于被動態句的末尾，說明是什么人或物應對有關事件負責。
e.g. the village was destroyed by a bomb.
這個村莊毀于炸彈。
the painting is very valuable. it was painted by van gogh.
這幅畫很值錢，它是梵•高畫的。
其它用法補充
1.“it + 被動語態+ that 從句”。表示謹慎或不太肯定的語氣。常用于該結構的動詞有：say, think, believe, agree, expect, consider, feel, know, decide, report, suggest, prove 等。
e.g. it is said that prices will rise again this month.
據說本月物價還將上漲。
it is thought that about a million dogs are born each year.
據認為每年約有一百條狗出生。
it is reported that all the passengers died in the crash.
據報導所有乘客在那次飛機墜毀中遇難。
it is agreed that we will have two weeks holiday this year.
2. 用于通告標題廣告等的被動態往往省去助動詞be。
e.g. no chinese spoken here.
shoes repaired.
famous painting stolen. 名畫被盜。