被動語態是動詞的一種形式，用以表示主語和謂語之間的關係。當主語是謂語動作的執行者，則為主動語態；當主語是謂語動作的承受者，則為被動語態。
例如：They asked the visitors not to touch the exhibits.
The visitors were asked not to touch the exhibits.
一、被動語態的構成
被動語態由助動詞be + 過去分詞構成，時態通過be表現出來。如：
一般過去時的被動語態：was / were+過去分詞。例如:
Many trees were planted on the hill yesterday.
現在進行時的被動語態：am/is/are+being+過去分詞。例如:
A new teaching building is being built in our school.
注：含情態動詞的被動語態：情態動詞+be+過去分詞。例如：
Your homework must be handed in now.
二、使用被動語態時的注意事項
1.“get + 過去分詞”也可以表示被動語態，其中get與be一樣起助動詞作用。該結構一般用來談論主語遭受到的變化或不好的事件。例如：
Unlike humans, they never get lost and can always find their way back.
2.動詞帶有雙賓語的主動結構在變為被動結構時，可以把其中的一個賓語變為主語，另一賓語仍然保留在謂語後面。通常變為主語的是間接賓語。例如：
His mother gave him a present for his birthday.
→ He was given a present by his mother for his birthday.
(也可改為A present was given to him by his mother for his birthday.)
3.當“動詞+賓語+賓語補足語”結構變為被動結構時，將賓語變為被動結構中的主語，其餘不動。例如：
Someone caught the boy smoking a cigarette in the classroom.
→ The boy was caught smoking a cigarette in the classroom.
4.在使役動詞have, make, let以及感官動詞see, watch, notice, hear, feel, observe等後面用不定式作賓語補足語時，在主動結構中不定式to通常省略，但變為被動結構時，要加to。例如：
Someone saw a stranger walk into the building.
→ A stranger was seen to walk into the building.
5.有些由“動詞＋介詞”、“動詞＋副詞”構成的動詞詞組，也可以用於被動結構，但要把它們看作一個整體，不能分開，其中的介詞或副詞也不能省略。例如：
Engineers can see how it works and make changes before construction is carried out.
6.一些表示“據說”或“相信”的動詞如believe, consider, expect, hope, know, report, say, suggest, suppose, think等可以用於句型“It＋be動詞＋過去分詞＋that從句”或“主語＋be動詞＋過去分詞＋to do sth.”。例如：
Since it is believed that strong smells can affect the senses, volunteers were required not to eat or drink for eight hours before the experiment.
Loulan is believed to have been gradually covered over by sandstorms from AD 200 to AD 400.
三、謂語動詞的主動形式表示被動意義
1. 英語中有很多動詞如 break, clean, lock, open, sell, read, wash等，當它們用來描述主語（某一事物）的特性時，常用其主動形式表達被動意義，此時主語通常是物。例如：
This kind of cloth washes easily. It is popular with young ladies, so it sells well.
值得注意的是，主動形式表被動意義強調的是主語的特徵，而被動語態則強調外界作用造成的影響。試比較：
The door won’t lock.（門本身有毛病）
The door won’t be locked. （不會有人來鎖門,指“門沒有鎖”是人為原因）
2. 連繫動詞沒有被動形式, 但有些表示感受或感官的連繫動詞（如feel, sound, taste, look, smell等）常以主動形式表示被動意義。例如：
I can’t see your face, but you sound young. How old are you?
3. 動詞want，need，require之後的動詞和句子的主語是邏輯動賓關係時，常用v-ing的主動形式表被動意義。例如：
The table needs repairing. (The table needs to be repaired)
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