不定式的“主动表被动”

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 computers 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 overcome.
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 persuad
e.
e. Wit h 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 mai
d.
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, comfortable, fit, dangerous, interesting, important等等
如：The river is dangerous to swim in.
The box is too heavy for the boy to carry.
The room is comfortable to live in.
The problem is difficult to work out.
当上述形容词在句中作宾语补足语，后接不定式时，不定式也用主动表被动
如：I found him easy to get along with.
They don’t think the ga me interesting to play.
3. There be 句型中，用来修饰主语的不定式多用主动式
如：There’s nothing to do now. ( = We have nothing to do now)
There’s nothing to see. ( nothing worth seeing)
注意：若用不定式的被动式，则表示不同的含义
比较：There’s nothing to be done. (= We can do nothing now)
There’s noth ing to be seen. ( nothing there at all)
而to let, to blame, to seek等不定式，多以主动式表被动意义
如：This flat is to let.
I am to blame for it.
动词不定式是动词的一种非谓语形式，它有时态的变化，有主动和被动之分。

当不定式的逻辑主语为不定式所表示动作的承受者时，通常需用不定式的被动形式。

如：he asked to be sent to the front. (他请求被派往前线。

)
但是，在下列情况下，常用不定式的主动形式来表示被动的含义：
1. 在“形容词+ 不定式”结构作表语、宾补和定语时，其中形容词多为表示性质的词，如：easy, hard, good, difficult, interesting等。

如：these apples are good to eat. 这些苹果很好吃。

i find the lecture difficult to understand. 我发现这个报告很难懂。

he is a man easy to get on with. 他是一个容易相处的人。

2. 在too...to...结构中。

如：the passage is too hard to translate. 这一段太难，无法翻译。

the box is too heavy to move. 这个箱子太重，搬不动。

3. 在“疑问代词+ 不定式”结构中。

如：i don't know what to do next. 我不知道下一步该做什么。

she will tell you which bus to take. 她会告诉你坐哪路公共汽车。

4. 在不定式作定语，与被修饰词之间有动宾关系，而与句中的另一名词或代词之间有主谓关系时。

如：i have a meeting to attend today. 今天我有个会议要参加。

do you have anything to say? 你有什么话要
说吗？
he gave me some books to read. 他给了我一些书看。

但如果没有这种主谓关系，则需要用不定式的被动形式。

如：i'm going to beijing next week. do you have anything to be taken to your parents?
下周我要去北京，你有什么东西(让我)捎给你父母吗？
5. 在下列句型中，to let, to blame, to seek等用不定形式表示被动含义。

如：the house is to let. 这栋房子要出租。

who is to blame for it? 这得怪谁？
the reason is not far to seek. 理由不难找到。

在英语学习中，有许多地方用主动表被动，这对于大多数学生来说是一个难点，不好掌握。

其实主动表被动是指形式无被动结构而含被动含义的主动形式，即句中某个名词或代词与某个动词存在逻辑动宾关系或为被动关系，用主动结构表被动含义。

用主动结构表示被动含义的情况有：
1. be worth＋doing值得做…… 例如：
The novel is worth reading again.
The film is worth seeing.
2. need（want / require）+ doing等于need（want / require）+to be done 需要做……例如：
My watch needs repairing（＝to be repaired）.
The house wants painting（＝to be pained）.
3. 某些与can’t, won’t等连用的不及物动词，如move, lock, shut, open等，常用主动结构表被动含义, 例如：
It can’t move.
Th e door won’t shut.
The window won’t open.
4.某些可以和well, easily, smoothly等副词连用的不及物动词如read, write, wash, clean, draw, burn, cook, sell, lock, open, shut等，且主语是非生命的名词或代词，用主动结构表被动含义。

例如：
This kind of book sells well.
The pen writes smoothly.
The cloth washes well.
The poem reads smoothly.
The table doesn’t clean easily.
This kind of rice cooks more easily than that kind.
That door shuts well.
5. 主语＋be＋adj.＋to do的结构中，动词不定式常用主动结构表被动含义，这些表语形容词有hard, difficult, easy, fit, necessary, dangerous, comfortable, heavy等。

例：The problem is hard to solve.
The chair is comfortable to sit on.
I find the water in the well fit to drink.
6. 有些系动词，如: taste, sound, prove, feel, look, smell, remain, appear等，常用主动结构表示被动含义。

例如：
The flower looks ugly.
What you said sounds reasonable.
The dish smells delicious.
The food tastes good.
The story proved quite false.
She remains silent.
This material feels soft.
7.有些不定式，如：to let, to blame, to rent, remain to do等常用主动结构表示被动含义。

例如：
The taxi is to rent.
Much remains to find.
Who is to blame for starting the fire?
The house is to let.
8. “主语+have / has + 名词+ to do”结构，也用主动结构表被动含义，此时主语与to do 存在逻辑上的主谓关系，to do 与宾语存在逻辑上的动宾关系。

例如：
He has many problems to solve.
Mr. White has lots of things to do.
I have a room to live in.
9.介词on, under等+名词构成介词短语表示被动意义。

例如：
①under＋n.结构，表示某事在进行中。

如：under control, under repair, under discussion
等。

例如：
The fire was under control at last.
②on +名词结构，表示“在从事……中”。

如：on sale, on show等。

例如：
Many new types of cars are on show in Beijing.
10.在too…to…和enough to do 结构中，不定式用主动形式表示被动含义。

例如：The box is too heavy to carry.
The room is not big enough to have a meeting in.。