被 structure

被字句 (bèizìjù) is used to express the passive in modern Mandarin Chinese. In passive sentences, the object of an action becomes the subject of the sentence, and what would have been the subject of the normal (active voice) sentence, the "doer" of the action, becomes secondary, and may or may not be included in the passive sentence. Let us take a look of these sentences of passive voice in English:

• The boy ate the pizza. (normal sentence in the active voice; note that "pizza" is the object of the verb "ate")
• The pizza was eaten by the boy. (the same sentence in the passive voice; "pizza" is now the subject, and "the boy" is the "doer")
• The pizza was eaten. (also in the passive voice, but with the "doer" omitted)

Now let's see those same sentences in Chinese:

• 男孩儿吃了比萨饼。(the original sentence)
• 比萨饼被男孩儿吃了。(the passive sentence)
• 比萨饼被吃了。(the passive sentence, with no "doer")

You may wonder why we use passive voice. Here are the reasons:

1) To shift emphasis from the "doer" of the action to the one affected by that action.

• 牛奶被喝了。
• 老师被气哭了。

2) To avoid having to mention the "doer" of the action, either because it is unknown, or for other reasons.

• 他的自行车被偷了。
• 他的手机被弄坏了。

How to form a 被字句 is very simple. The structure is Subject + 被 + （Doer） + Verb Phrase. For example, 

• 牛奶被王家明喝了。
• 窗户被打开了。

Please change the following sentences into 被字句.

1. 蚂蚁吃了一条大虫。
2. 我收拾干净了我的房间。
3. 雨水淋湿了我的衣服。
4. 我摔坏了我的手机。
5. 小猫捉到了一只老鼠。
6. 我找到了爸爸的眼镜。
7. 大卫把弟弟送回了家。
8. 妈妈把垃圾丢掉了。
9. 医生把他的病治好了。
10. 杰克把字典借走了。

Advanced usage: 被和谐 (to be harmonized)