to do 不定式主动表被动的用法 比如他很容易受骗 He is easy to take in.O

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He is easy to take in.easy的用法
参考：1.动词不定式在名词后面作定语,不定式和名词之间有动宾关系时,又和句中另一名词或代词构成主谓关系,不定式的主动形式表示被动含义.
　　例 I have a lot of things to do this afternoon． (to do与things是动宾关系,与I是主谓关系.)
　　试比较：I’ll go to the post office.Do you have a letter to be posted?( 此处用不定式的被动语态作定语表明you不是post动作的执行者.)
2.在某些“形容词＋不定式”做表语或宾语补足语的结构中,句子的主语或宾语又是动词不定式的逻辑宾语时,这时常用不定式的主动形式表达被动意义.这些形容词有nice,easy,fit,hard,difficult,important,impossible,pleasant,interesting等.
　　例This problem is difficult to work out .（可看作to work out省略了for me）.
3． 在too… to…结构中,不定式前面可加逻辑主语,所以应用主动形式表示被动意义.
　　例This book is too expensive (for me) to buy.
4.在there be…句型中,当动词不定式修饰名词作定语时,不定式用主动式作定语,重点在人,用被动形式作定语,重点在物.
　　例There is no time to lose（to be lost）．（用 to lose可看成for us to lose；用to be lost,谁 lost time不明确.）
5.在be to do结构中的一些不定式通常应用主动表主动,被动表被动.然而,由于古英语的影响,下列动词rent,blame,let等仍用不定式的主动形式表示被动意义.
　　例 Who is to blame for starting the fire?
He is easy to take in.属于第二种用法.
======以下答案可供参考======
供参考答案1:
同学们都知道动词不定式有主动式和被动式，即 “ to do和 to be done” 之分，但在实际使用中常有用主动形式表示被动含义的情况，比如：
1). I have a lot of housework to do today.
2). There are so many types of puters for you to choose.
3). I think English is not so hard to learn.
上述三例中的不定式与其前面的名词之间都存有被动关系，但是都用了不定式的主动式表示被动意义。那么究竟在哪些情行下可用不定式的主动表示被动呢？
1. 动词不定式的逻辑主语在句子中出现或暗含在句中
如：a. We have many difficulties to overe.
b. Give him some storybooks to read.
c. They didn’t think that a proper measure (for them) to take.
d. He is not easy (for anyone) to persuade.
e. With so many trees to plant, he got up at 5 o’clock the next morning.
注意：若句子的主语并非不定式的逻辑主语时，不定式则必须用被动式
如：a. I’ll go to New York. Have you anything to be taken to your wife there?
b. I have no letter to be typed. Thank you all the same.
c. “Have you any clothes to be washed, sir?” asked the maid.
a句中take的逻辑主语为I而不是you ; b句中type的逻辑主语是you 而不是I；c句中wash的逻辑主语是 maid 而不是I。
2. 在 Sth. / Sb. + adj. + to do 结构中， 若形容词为：easy, difficult, hard, heavy, light, good, nice, pleasant, fortable, fit, dangerous, interesting, important等等
如：The river is dangerous to swim in.
The box is too heavy for the boy to carry.