由不及物動(dòng)詞+介詞或副詞形成的被動(dòng)語態(tài)

Many trees are cut down by workers.

不及物動(dòng)詞不能跟賓語，當(dāng)然就沒有被動(dòng)語態(tài)了，但有的不及物動(dòng)詞，后面跟上一個(gè)介詞或副詞后（即形成所謂的動(dòng)詞短語），其作用和一個(gè)及物動(dòng)詞一樣，這樣，在變成被動(dòng)語態(tài)時(shí)，千萬不要把介詞或副詞去掉。

例如：

She looks after them.

（○）They are looked after by her.

（×）They are looked by her.

We laughed at him.

He was laughed at（by us）.

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動(dòng)詞短語的被動(dòng)語態(tài)

take care of（照看）→be taken care of

cut down（砍倒）→be cut down

laugh at（嘲笑）→be laughed at

look after（照料）→be looked after

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被動(dòng)語態(tài)的動(dòng)詞短語

以下這些短語本身即是被動(dòng)語態(tài)的形式，不需再加“by”。

be covered with??????????????????用……覆蓋著

be surprised at????????????????????對……感到驚奇

be known to???????????????????????出名

be interested in??????????????????對……感興趣

be made of（from）??????????用……制造的