被动语态的用法：

被动语态表示一种主语和谓语之间的关系，当主语是动作的承受者时， 就需要用到被动语态，汉语中所说的，“汽车被撞坏了”“钢笔被修好了” 等句子就是一种被动语态的句子，在汉语中常用“被”“由”等词来表示这种被动语态。在英语中则用动词的被动语态形式来表示。被动语态中还可用 by 短语加在句后表示被动语态中动作的发出者。也就是谓语动词动作的逻辑上的主语，被动语态常用在下列情况。

1) 不知道谁是谓语动词动作的执行者时，或者没有必要说出谁是执行者时。

The glass was broken last night.

玻璃昨天被打破了。

His bike has been stolen.

他的自行车被偷了。

He was asked to go there once more.

他被要求再去那儿一次。

The bag was put into the box.

袋子放在了箱子里。

2) 为了强调或突出动作的承受者时。

The plan has been sent to the headmaster.

计划已经送给校长了。

Kilinton was elected the President of U.S.A.

克林顿被选为美国总统。

Five people were hurt in the explosion.

五个人在这次爆炸中受伤。

A new building was set up in a short time.

新大楼短期就建成了。

3) 被动语态也可以说出动作的执行者，构成如下：

动作承受者 + be + 过去分词 + by + 动作执行者。

The picture was praised by everybody.

照片得到了大家的好评。

The classroom was cleaned by us.

教室被我们打扫过。

The bridge was built by workers from Shanxi.

这座桥是山西的工人建的。

The little boy was found by the police.

小孩被警察找到了。

有关被动语态的几个问题：

1) "be + 过去分词" 并非都是被动语态，系动词 be, feel, seem,look,等词后面的过去分词已转化为形容词，作表语用，表示某种状态。

I'm interested in mathematics.

我对数学感兴趣。

He seems unsatisfied with his work.

他看起来对他的工作不满意。

We are determined to catch up with the developed countries.

我们决心要赶上发达国家。

The song is called "Don't forget me".

歌曲的名字叫“勿忘我”。

某些动词用主动语态来表示被动含义。

The food tastes good.

食物很香。

It smells strange.

这有怪味。

The stone feels very cold.

石头摸起来很冷。

The woman's clothes sell well.

女装卖的快。

3) 一般情况下，及物动词才能构成被动语态，但有些不及物动词组成短语后，也可构成被动语态。

He was looked down upon because of his egoism.

他因自私而受人冷落。

The children were taken good care of in the the orphanage.

孩子们在孤儿院受到了良好的照顾。