英语语法 动词不定式1
动词不定式由to+动词原形构成。这里的to是不定式标志，没有词义。不定式具有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用。
常见的形式如表所示(以及物动词do为例)，不及物动词没有被动语态。
时态语态 主动 被动
一般式 to do to be done
进行式 to be doing /
完成式 to have done to have been done
完成进行式 to have been doing /
7.1 有些动词可以用不定式作宾语，大致上有三种情况。
1) 有些及物动词用不定式作宾语，结构为动词+不定式。例如：
afford aim agree arrange ask decide
bother care choose demand desire determine
elect endeavor hope fail help learn
long 渴望 mean manage offer plan pretend
refuse tend undertake expect hate intend
例如：
The driver failed to see the other car in time. 司机没能及时看见另一辆车。
He offered to help me. 他表示愿意帮助我。
2)有些动词除了可以用不定式作宾语，还用不定式作补语，即有动词+宾语+不定式的结构。例如：
ask choose expect help beg intend
like/love need prefer prepare want wish
例如：
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3) 有些动词或动词词组可以用动词+疑问词+不定式的结构作宾语。例如：
decide know consider forget learn remember
show, wonder find out tell inquire explain
例如：
Please show us how to do that. 请演示给我们如何去做。
There are so many kinds of tape-recorders on sale that I cant make up my mind which to buy.
有这么多的录音机，我都拿不定主意买哪一种。
7.2 不定式作补语
1) 有些有动词+宾语+不定式的结构。例如：
advise allow cause challenge command compel
drive 驱使 enable encourage forbid force impel
induce instruct invite like/love order permit
make let have want get warn
persuade request send tell train urge
例如;
Father will not allow us to play on the street. 父亲不让我们在街上玩耍。
The officer ordered his men to fire. 长官命令士兵开火。
注意：有些动词如make，have，get，want等可用不定式作做宾补，也可用分词作宾补。现在分词表达主动，也表达正在进行，过去分词表达被动。
2) 有些有动词+宾语+不定式的结构，不定式的动词往往是be，不定式一般可以省去。例如：
consider find believe think declare(声称) appoint
guess fancy(设想) guess judge imagine know
例如：
We believe him to be guilty. 我们相信他是有罪的。
We know him to be a fool. 我们知道他是个笨蛋。(to be 不能省去)
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：C. 一般没有consider+宾语+be以外不定式的结构，也没有consider+宾语+doing的结构，排除A、B、D。consider用动词be以外的不定式作宾补时，一般要求用不定式的完成式，故选C。
3) 有些动词可以跟there +to be的结构。例如：
believe expect intend like love mean
prefer want wish understand
例如：
We didnt expect there to be so many people there. 我们没料到会有那么多人在那里。
You wouldnt want there to be another war. 你不至于想让另外一场战争发生吧。
7.3 不定式作主语
不定式作主语，往往用it作形式主语，真正的主语不定式放至句子的后面。
例如：Its so nice to hear your voice. 听到你的声音真高兴。
Its necessary for you to lock the car when you do not use it. 不用车的时候，锁车是有必要的。
Its very kind of you to help us. 他帮助我们，他真好。
It seemed selfish of him not to give them anything. 他不给他们任何东西，这显得太自私了。
但是，用不定式作主语的句子中还有一个不定式作表语时，不能用It is to的句型。另外，这样的句子，不能用动名词作表语。例如：
(对)To teach is to learn.
(错)It is to learn to teach.
(错)To teach is learning.
(错)Teaching is to learn.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词，其后应有必要的介词。当动词与介词连用时，常位于形容词+动词不定式结构的末尾。 动词不定式由to+动词原形构成。这里的to是不定式标志，没有词义。不定式具有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用。
常见的形式如表所示(以及物动词do为例)，不及物动词没有被动语态。
时态语态 主动 被动
一般式 to do to be done
进行式 to be doing /
完成式 to have done to have been done
完成进行式 to have been doing /
7.1 有些动词可以用不定式作宾语，大致上有三种情况。
1) 有些及物动词用不定式作宾语，结构为动词+不定式。例如：
afford aim agree arrange ask decide
bother care choose demand desire determine
elect endeavor hope fail help learn
long 渴望 mean manage offer plan pretend
refuse tend undertake expect hate intend
例如：
The driver failed to see the other car in time. 司机没能及时看见另一辆车。
He offered to help me. 他表示愿意帮助我。
2)有些动词除了可以用不定式作宾语，还用不定式作补语，即有动词+宾语+不定式的结构。例如：
ask choose expect help beg intend
like/love need prefer prepare want wish
例如：
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3) 有些动词或动词词组可以用动词+疑问词+不定式的结构作宾语。例如：
decide know consider forget learn remember
动词不定式由to+动词原形构成。这里的to是不定式标志，没有词义。不定式具有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用。
常见的形式如表所示(以及物动词do为例)，不及物动词没有被动语态。
时态语态 主动 被动
一般式 to do to be done
进行式 to be doing /
完成式 to have done to have been done
完成进行式 to have been doing /
7.1 有些动词可以用不定式作宾语，大致上有三种情况。
1) 有些及物动词用不定式作宾语，结构为动词+不定式。例如：
afford aim agree arrange ask decide
bother care choose demand desire determine
elect endeavor hope fail help learn
long 渴望 mean manage offer plan pretend
refuse tend undertake expect hate intend
例如：
The driver failed to see the other car in time. 司机没能及时看见另一辆车。
He offered to help me. 他表示愿意帮助我。
2)有些动词除了可以用不定式作宾语，还用不定式作补语，即有动词+宾语+不定式的结构。例如：
ask choose expect help beg intend
like/love need prefer prepare want wish
例如：
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3) 有些动词或动词词组可以用动词+疑问词+不定式的结构作宾语。例如：
decide know consider forget learn remember
show, wonder find out tell inquire explain
例如：
Please show us how to do that. 请演示给我们如何去做。
There are so many kinds of tape-recorders on sale that I cant make up my mind which to buy.
有这么多的录音机，我都拿不定主意买哪一种。
7.2 不定式作补语
1) 有些有动词+宾语+不定式的结构。例如：
advise allow cause challenge command compel
drive 驱使 enable encourage forbid force impel
induce instruct invite like/love order permit
make let have want get warn
persuade request send tell train urge
例如;
Father will not allow us to play on the street. 父亲不让我们在街上玩耍。
The officer ordered his men to fire. 长官命令士兵开火。
注意：有些动词如make，have，get，want等可用不定式作做宾补，也可用分词作宾补。现在分词表达主动，也表达正在进行，过去分词表达被动。
2) 有些有动词+宾语+不定式的结构，不定式的动词往往是be，不定式一般可以省去。例如：
consider find believe think declare(声称) appoint
guess fancy(设想) guess judge imagine know
例如：
We believe him to be guilty. 我们相信他是有罪的。
We know him to be a fool. 我们知道他是个笨蛋。(to be 不能省去)
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：C. 一般没有consider+宾语+be以外不定式的结构，也没有consider+宾语+doing的结构，排除A、B、D。consider用动词be以外的不定式作宾补时，一般要求用不定式的完成式，故选C。
3) 有些动词可以跟there +to be的结构。例如：
believe expect intend like love mean
prefer want wish understand
例如：
We didnt expect there to be so many people there. 我们没料到会有那么多人在那里。
You wouldnt want there to be another war. 你不至于想让另外一场战争发生吧。
7.3 不定式作主语
不定式作主语，往往用it作形式主语，真正的主语不定式放至句子的后面。
例如：Its so nice to hear your voice. 听到你的声音真高兴。
Its necessary for you to lock the car when you do not use it. 不用车的时候，锁车是有必要的。
Its very kind of you to help us. 他帮助我们，他真好。
It seemed selfish of him not to give them anything. 他不给他们任何东西，这显得太自私了。
但是，用不定式作主语的句子中还有一个不定式作表语时，不能用It is to的句型。另外，这样的句子，不能用动名词作表语。例如：
(对)To teach is to learn.
(错)It is to learn to teach.
(错)To teach is learning.
(错)Teaching is to learn.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词，其后应有必要的介词。当动词与介词连用时，常位于形容词+动词不定式结构的末尾。 动词不定式由to+动词原形构成。这里的to是不定式标志，没有词义。不定式具有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用。
常见的形式如表所示(以及物动词do为例)，不及物动词没有被动语态。
时态语态 主动 被动
一般式 to do to be done
进行式 to be doing /
完成式 to have done to have been done
完成进行式 to have been doing /
7.1 有些动词可以用不定式作宾语，大致上有三种情况。
1) 有些及物动词用不定式作宾语，结构为动词+不定式。例如：
afford aim agree arrange ask decide
bother care choose demand desire determine
elect endeavor hope fail help learn
long 渴望 mean manage offer plan pretend
refuse tend undertake expect hate intend
例如：
The driver failed to see the other car in time. 司机没能及时看见另一辆车。
He offered to help me. 他表示愿意帮助我。
2)有些动词除了可以用不定式作宾语，还用不定式作补语，即有动词+宾语+不定式的结构。例如：
ask choose expect help beg intend
like/love need prefer prepare want wish
例如：
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3) 有些动词或动词词组可以用动词+疑问词+不定式的结构作宾语。例如：
decide know consider forget learn remember
