被动语态
语态
英语语态分为两种：主动语态和被动语态。
“兔子咬人了！”
”谁被兔子咬了？“
在一句话中，想要强调谁，谁就会充当主语。如果强调动作的执行者，譬如兔子做出咬人的举动，句子就会用主动语态。如果强调动作的承受者，譬如谁被咬，句子就倾向用被动语态。
被动语态的构成也是通过谓语动词的变化完成的，不妨通过五种基本句型来看看它们的被动语态是怎么演化的。
基本句型
主 + 谓
The rabbit slept.
该剧 slept 是个不及物动词，没有宾语，不存在动作的承受者这个概念，自然就没有被动语态了。
主 + 谓 + 宾
The rabbit ate the carrot.
主语 the rabbit 是动作 ate 的执行者，the carrot 是动作 ate 的承受者，如果变成被动语态，就是强调动作的承受者，让 the carrot 成为主语。其中被动语态的构成为“be + 动词过去分词”。如果需要表明动作的执行者是谁，就要借助“by + 动作执行者”。所以，我们得到：
Teh carrot was eaten by the rabbit.
很多情况下，无需表明“被谁…”这一概念，例如：
A carrot was eaten.
回想一下在非谓语动词里，过去分词作主语补语（表语）的句子：
The rabbit was frightened by the wolf.
所以，过去分词表被动的意义和被动语态脱不了关系。
主 + 谓 + 宾 + 宾
The rabbit gave the carrot to the wolf.
在这个句子里有两个宾语，直接宾语 the carrot 和间接宾语 the wolf。如果强调间接宾语 the wolf：
The wolf was given the carrot by the rabbit.
如果强调直接宾语 the carrot：
The carrot was given to the wolf by the rabbit.
当然，如果都知道是兔子给狼胡萝卜，可以把 by + 动作执行者这部分去掉。所以上面两个句子可以简写成：
The wolf was given the carrot.
The carrot was given to the wolf.
如果这个句子主动形式写成“主语+谓语+间接宾语+直接宾语”的形式，那 to 就消失了。
The rabbit gave the wolf the carrot.
但在强调直接宾语 the carrot 变被动句时，可不能是：
The carrot was given the wolf (by the rabbit).
它和之前那句代介词 to 的主动句变被动语态是一样的，所以应该还是：
The carrot was given to the wolf (by the rabbit)+
千万不要漏掉 to。
主 + 谓 + 宾 + 宾补
The wolf invited the rabbit to her party.
改为被动态：
The rabbit was invited to the party by the wolf.
有时需要特别注意，再看一个例子：
The rabbit made the wolf laught.
make 等后接的是省略了 to 的动词不定式，这种不带 to 的动词不定式也被成为裸不定式。
所以原句实际上相当于：
The rabbit made the wolf to laught.
一旦省略了 to 的动词不定式作宾补，改成被动语态时要把 to 还原。 所以改成被动语态应该是：
The wolf was made to laugh (by the rabbit).
主 + 系 + 表（主语补语）
The rabbit is smart.
这种句型没有办法变成被动语态。
复杂用法
其实被动态可以更复杂，如果被动态和动态、语气、情态助词相结合的话，就会产生一系列“化学反应”，比如：
The rabbit has eaten the carrot.
-> The carrot has been eaten by the rabbit.
-> The carrot has not been eaten by the rabbit.
-> Has the carrot been eaten by the rabbit.
The rabbit would have eaten the carrot.h
-> The carrot would have been eaten by the rabbit.
-> The carrot would not have been eaten by the rabbit.
-> Would the carrot have been eaten by the rabbit.
The rabbit might eat the carrot.
-> The carrot might be eaten by the rabbit.
-> The carrot might not be eaten by the rabbit.
-> Might the carrot be eaten by the rabbit.
归根结底，这些变位主要是针对构成被动语态所需的 be 动词的变位。