1． 不定式（to do）是由動(dòng)詞轉(zhuǎn)化而來的一種形式，仍保留有動(dòng)詞的特征：
○1有自己的賓語(yǔ)和狀語(yǔ)。不定式與自己的賓語(yǔ)和狀語(yǔ)構(gòu)成不定式短語(yǔ)。
○2有時(shí)態(tài)和語(yǔ)的變化，但它是非謂語(yǔ)動(dòng)詞，不能做謂語(yǔ)，可作除謂語(yǔ)
以外的成份：主、賓、表、定、狀、補(bǔ)。
2． 時(shí)態(tài)和語(yǔ)態(tài)：
語(yǔ)態(tài) 時(shí)態(tài) 主動(dòng)語(yǔ)態(tài) 被動(dòng)語(yǔ)態(tài)
一般式 to do to be done
完成式 to have done to have been done
進(jìn)行式 to be doing
(注)進(jìn)行式(to be doing)常用在如下動(dòng)詞后：seem, appear, happen,
think, consider, pretend, want等。
Eg. He happened to be sleeping when I went into the room.
◆時(shí)態(tài)：○1一般式：不定式動(dòng)作與謂語(yǔ)動(dòng)作（幾乎）同時(shí)發(fā)生，
或發(fā)生在謂語(yǔ)動(dòng)作之后。
○2完成式：不定式動(dòng)作發(fā)生在謂語(yǔ)動(dòng)作之前。
○3進(jìn)行式：謂語(yǔ)動(dòng)作發(fā)生時(shí)，不定式動(dòng)作正在進(jìn)行。
Eg. I’m glad to see you.
I’m glad to have received your letter.
He pretended to be sleeping.
◆語(yǔ)態(tài)：vi.不定式只有主動(dòng)語(yǔ)態(tài)，無(wú)被動(dòng)語(yǔ)態(tài)。
vt. 不定式有主被動(dòng)語(yǔ)態(tài)。
不定式的邏輯主語(yǔ)是不定式協(xié)作的執(zhí)行者，要用主動(dòng)語(yǔ)態(tài)。
不定式的邏輯主語(yǔ)是不定式協(xié)作的受動(dòng)者，要用被動(dòng)語(yǔ)態(tài)。
eg. I’m glad to meet you.
He disliked to be praised in public.
3． 句法功能：
1） 作主語(yǔ)：To smoke is a bad habit.(不定式作主語(yǔ)，謂語(yǔ)動(dòng)詞用單數(shù)）
不定式短語(yǔ)作主語(yǔ)時(shí)通常后置，而用it作形式主語(yǔ)，
且常構(gòu)成以下句型：
It+be+adj./n.+to do
It+be+adj./n.+ for sb.+to do eg. It’s nice of you to help me.
of It’s important for me
to learn English.
It takes/took sb. time to do
It costs/cost sb. money to do.
2)作賓語(yǔ)，接不定式作賓語(yǔ)的動(dòng)詞：
agree, decide, hope, manage, plan, prepare, pretend, promise,
refuse, want, wish.
begin/start/like/love/hate/continue/prefer +to do 意思差別不大。
doing
like to do具體的一次性的動(dòng)作。
like doing 習(xí)慣性的動(dòng)作
eg. I like watching TV, but I don’t like to watch TV today.
stop to do remember to do
doing doing
forget to do go on to do
doing doing
try to do mean to do
doing doing
eg. Waving one’s hand means saying “Goodbye”.
Don’t be angry with Tom. He doesn’t mean to hurt you.
I remember _____ the windows, so you don’t have to do it.
I remember_____the windows, so I’ll do it at once.
3）作賓語(yǔ)補(bǔ)足語(yǔ)：
He advised me to stop smoking.
V． + 賓語(yǔ) + 賓補(bǔ)
作賓語(yǔ)補(bǔ)足語(yǔ)的不定式有時(shí)可以省to，主要包括以下動(dòng)詞：
A． 使役動(dòng)詞：make, let, have,（let, have不用于被動(dòng)語(yǔ)態(tài)）
B． 感官動(dòng)詞：see, hear, notice, feel, watch, look at, listen to, find,但被動(dòng)語(yǔ)態(tài)
要加上to.
C． help后可省可不省to: help sb. (to) do
4)定語(yǔ)：放在n./pron.之后
eg. She has a lot of work to do.
（注）○1不定式中的動(dòng)詞如不及物，后應(yīng)加上適當(dāng)?shù)慕樵~
Eg. Have you enough paper to write on?
She is a very nice person to work with.
○2there are句型中的不定式（to do）作定語(yǔ)，可用主動(dòng)或被動(dòng)。
eg. There be a meeting to attend.
to be attended
5）狀語(yǔ)： in order to do
○1目的狀語(yǔ)： so as to do
to do
○2結(jié)果狀語(yǔ)： only to do eg. He woke up only to find he
was locked in the room.
too+adj.+to do
enough to do eg. He is old enough to go to school.
6）表語(yǔ)：His wish is to be an artist.
4．其它注意事項(xiàng)：
1）否定式：not to do eg. I’m sorry not to have accepted your advice.
2）不定式可用主動(dòng)形式表示被動(dòng)意義的情況：
○1當(dāng)不定式的邏輯主語(yǔ)以動(dòng)作執(zhí)行者的身份出現(xiàn)在句中時(shí)：
Eg. Parents should give the children some housework to do.
○2“be+ adj.+to do”
eg. The result is hard to tell.
The book is interesting to read.
○3There be結(jié)構(gòu)中，作定語(yǔ)的不定式可用主動(dòng)也可用被動(dòng)形式。
eg. There are many goods to ship in the port.
○4be to blame習(xí)慣用法中：
eg. I’m to blame for this. 我為此將受到譴責(zé)。
This house is to let. 這房子要出租。
3）for/of sb. to do 叫做不定式的復(fù)合結(jié)構(gòu)。
4）wh- + to do 叫做帶特殊疑問詞的不定式，常放在know/show/ learn
作主、賓、表。
5）主句部分出現(xiàn)動(dòng)詞do, 表語(yǔ)的不定式可省to.
eg. What I want to do is run a night school.
6)but/except 前的謂語(yǔ)動(dòng)詞有do，介詞后無(wú)to；前無(wú)do ，后有to
eg. I did nothing but repair my bike.
I will do anything but cook.
I have no choice but to wait.
7)and/or連接兩并列的不定式時(shí)，后一個(gè)不定式可省to
eg. To leave or stay is not decided.
8）want, need, require主語(yǔ)是物，不是人時(shí)，后面用doing
或to be done譯為“需要”
eg. The desk needs repairing to be repaired.
Your hair wants cutting/to be cut.
9）動(dòng)詞不定式的省略，動(dòng)詞可省，不定式符號(hào)“to” 不可省.