英语讲义【85】被动句中的动词形态

信箱里有一张装修商的传单，上面有这句话：

　　Exchange this leaflet for a free gift and also be entitle to a lucky draw with no purchase required.

　　这句话清楚吗？很清楚！问题是第二个并列分句的被动语态的动词形态“entitle”不对。为什么不对呢？这就要从主动语态（the active voice）和被动语态（the passive voice）的差别谈起。

　　在主动语态里，主语是动作的主角，如：

　　① I have just bought a new dictionary.
　　② They will invite you to dinner.

　　在被动语态里，宾语成为主角，原来的主语则靠边站，移至句后，如：

　　③ A new dictionary has just been bought by me.
　　④ You will be invited to dinner by them.

　　在被动语态的结构里，最重要的成分是接系动词“be”+主动词的过去分词（be+past participle of the principal verb）。③里的“has been bought”和④里的“will be invited”便是这个成分。根据这原则，“be entitle”就要改为“be entitled”才行。

　　现在多看看几个例子：

　　⑤ One must do the work properly.→The work must be properly done.
　　⑥ Someone took down the pictures.→The pictures were taken down.
　　⑦ Anne gave John a photo.→John was given a photo by Anne.

　　在⑤和⑥里，原来的主语不重要，所以在被动句中被省略了。在 ⑦里，我们看到两个宾语，一个是直接宾语（direct object）“a photo”，另一个是间接宾语（indirect object）“John”。直接宾语一定是“事物”；间接宾语就是“人物”。

　　这样的主动语态，有两种变法。除了“John was given a photo by Anne”之外，另一个方法是“A photo was given to John by Anne.”

　　在日常英语用途上，直接语态比间接语态用得多。但在下列情况中，则应采用被动语态：

　　㈠主语不详，如：

　　① A puppy was knocked down.
　　② Actions must be taken to improve the economic situation.

　　㈡突出宾语，如：

　　③ The gangster was sent to prison.
　　④ Two eye witnesses have been questioned.
　　⑤ All good students will be rewarded.

　　㈢不方便提到主语，如：

　　⑥ Some students are said to be often late for class.
　　⑦ The name of the suspect has been submitted to the police.

　　㈣动词习惯以被动式出现，如：

　　⑧ You are expected to work hard from now on.
　　⑨ The last train is scheduled to leave at 10p.m.
　　⑩ All loyal citizens are supposed to defend their country.

　　①—⑩这些被动句中的原有主语通常被省略，不出现。