大学英语3 笔记 Unit 1 Stories Lighting up the Hospital - PartV Grammar 不定式
动词不定式在句中不能作谓语用,属非谓语动词的一种。动词不定式由“to + 动词原形”构成,其否定形式“not to + 动词原形”。动词不定式虽然不能作谓语动词用,但是保留动词的特征,它可以带有所需要的宾语(如:to play tennis)或状语(如:to work hard)而构成动词不定式短语。
To see is to believe.(作主语)
It is not easy to learn English well.(it是形式主语,不定式短语是真正的主语)
My job is to take care of those kids.(作表语)
The poor man has no place to go now.(做定语)
I hope to go there again.(作宾语)
补充:常可接动词不定式作宾语的动词有:
agree(同意),hope(希望),decide(决定),need(需要),mean(打算),wish(希望),fail(失败),want(想要),begin(开始),would like(想要)等
XX to do sth
I find it so hard to change myself.(it 是形式宾语,不定式短语是真正的宾语)
I want you to be independent.(作宾语补足语)
She got up early to catch the first train.(作目的状语) # 事情还没有发生,起到的是一种目的
I'm so glad to meet you. (作原因状语)
I got to my office to find Jack waiting for me.(做结果状语)# 事情已经发生,起到的是一种结果
To be frank, I can't put up with you any longer.(作独立结构) # To be frank 实话告诉你吧
# 不定式的时态和语态
1. 不定式有时态的区分
1)一般式:一般现在时表示的动词,有时与谓语动词表示的动作同时发生,有时发生在谓语动词的动作之后。
He seems to know this. # 现在时,同时发生
I hope to see you again. = I hope that I'll see you again(可以替换为此从句) # 将来时,将来发生
2)完成式:表示的动作发生在谓语动词表示的动作之前。
I'm sorry to have given you so much trouble. # 它道歉之前,这些trouble已经出现,也就是后面的事情发生在道歉之前,所以用完成式
He seems to have caught a cold. # 着凉是先于他发现,所以这个也是一个完成式
3)进行式:表示动作正在进行,与谓语动词表示的动作同时发生
He seems to be eating something. 他视乎在吃东西
4)完成进行式:表示动作从过去某一时间开始一直延续到现在或离现在不远的时间。
She has been working on the problem for many year. 他很多年来一直致力于研究这个问题
2. 不定式由语态(即主动语态和被动语态)的区分。动词不定式用主动还是被动,关键要看动作与主语的关系来决定。
They give me a chance to visit your country. (主动语态) 他们给了我一个访问贵国的机会
I am very happy to be given a chance to visit your country. (被动语态) 很高兴被给予一个机会访问贵国
# 不定式“to”的省略
1. 感官动词(feel, hear, see, watch, notice等)后面的to 常省略,但是被动语态中的to不能省略
We heard him to sing every day. # (主动语态)初选感官动词,这里的to可以省略
He was heard to sing this song every day. # (被动语态)这里的to不能省略
2. 使役动词(have,let,make等)后面的to常省略,但是被动语态中的to 不能省略
I made to her figure out a solution in 15 minutes. # 这里的to可以省略;
She was made to deal with the matter at once. # 这里的to不能省略;
3. 不定式作标语时,一般要带to, 但若主语部分中含有do 的各种形式时, to 可省略。
We've missed the last bus. All we could do now is to walk home. # 这里的to可以省略
4. 当两个或多个不定式短语由连词and, but 或or 连接时,后一个或几个不定式符号to 常省略。但若表示对比、对照关系时,则不能省略。
He wants to move to France and to marry the girl. # 这里的to可以省略
The purpose of new technologies is to make life easier, not to make it more difficult. # 这里的to不能省略; 因为产生了对比
5. 当不定式用作介词except或except的宾语时,如果前有do,不定式要省略to。
There's little we can do except to wait. # 这里的to可以省略
I could do nothing except to agree. # 这里的to可以省略
6. 在why(not)...?之后的不定式要省略to.
Why to argue with him? He'll never change his mind.
PS: argue with 争论;和……争吵
Why not to take a holiday?
# 不定式的复合结构
1. It's + 形容词 + for + sb. + to do sth.
其中for sb. 常用语表示实物的特征或特典。常和以下形容词连用:
如:dangerous,easy,hard,diffcult,interesting,impossible等。
It's dangerous for children to swim in the river.
2. It's + 形容词 + of + sb. + to do sth.
其中of sb. 常用于表示任务的性格或品德。常和以下形容词连用:
如:good, kind,nice,clever,foolish
It was careless of you to do that.
# 不定式的特殊结构
1. “疑问词(who which,when,where,waht,how等)+ 不定式” 结构,在句中起名词作用。
Where to hold the meeting is not decided yet. (作主语)
My question is how to get there. (作表语)
I don't know what to do. (作宾语)
She told me where to find the earphone.(作宾语补足语)
2. “...too...to...”结构
1)表示“太....以至于不...”
He is too excited to speak.
2) 如在too前有否定词,则整个句子用否定词表达肯定,too后哪个词表达一种委婉含义,意为“不太”。
It's never too late to mend # 过而能改,善莫大焉;亡羊补牢,犹未晚也
3) 当too 前面有only, all, but时,意思是:非常...等于very.
I'm only too pleased to be able to help you. 能帮助你,我太高兴了。