<例句>
Three people were injured.
三个人受了伤。
<语法分析>
在动作的执行者不明确或没有必要提到的情况下，句子可以用被动结构。在动作的承受者或结果作为谈话的中心时，也用被动结构，这类句子畅游一个by引导的短语说明动作的执行者。动作的执行者很模糊时，如指people或one时，也可用被动结构。有时为了措辞上的需要，用被动结构可以避免说出动作的执行者。另外在公告、通知、新闻报道和报纸标题以及科技文章里常用被动结构。
<触类旁通>
(1) We are called on to take an active part in the movement.
我们被号召积极参加这项运动。
语法分析：动作的执行者不明确或没有必要提到的情况下，可以用被动结构。
(2) A peace treaty was finally signed.
最终签订了一项和约。
语法分析：没有必要提到动作的执行者，可用被动结构。
(3) When she was ill her children were looked after by neighbours.
她生病时，孩子们由邻居们照顾。
语法分析：动作的承受者或结果作为谈话的中心时，用被动结构。
(4) The house next door has been bought by someone.
隔壁房子有人买了。
语法分析：被动结构的句子常由一个by引导的短语说明动作的执行者，有时也可没有。
(5) It's hoped that such things would not happen again.
希望这样的事不再发生。
语法分析：为了措辞上的需要，用被动结构可以避免说出动作的执行者。
(6) She appeared on the stage and was warmly applauded by the audience.
她在台上出现，受到观众的热烈鼓掌。
语法分析：用被动结构可以使句子的得到更好的安排。
<巩固练习>
(1) When will the result _____[announce]?
(2) Rent has to _____[pay] in advance.
(3) A new public library is _____[build].
(4) This sort of advertisement _____[see] everywhere.
(5) She _____[believe] to have made an important discovery.
(6) The letter has _____[open]!
<参考答案>
(1) be announced (2) be paid (3) being built (4) is seen (5) was believed (6) been opened
