動(dòng)詞不定式概述
動(dòng)詞不定式指由to加上動(dòng)詞原形所構(gòu)成的一種非限定性動(dòng)詞，但在有些情況下to 可省略。動(dòng)詞不定式在語(yǔ)法功能上可作主語(yǔ)、賓語(yǔ)、表語(yǔ)、定語(yǔ)和狀語(yǔ)，如：
To ignore this dangerous signal would be a terrible mistake. (作主語(yǔ))
He promised not to tell anyone else about it. (作賓語(yǔ))
To treat comrades like enemies is to go over to the side of the enemy.(作表語(yǔ))
The manager announced his intention to retire.(作定語(yǔ))
The old man walked slowly on the ice in order not to fall down.(作狀語(yǔ))
不定式中的動(dòng)詞仍然具有動(dòng)詞的特性，可以有自己的賓語(yǔ)和狀語(yǔ)，另外雖然動(dòng)詞不定式在語(yǔ)法上沒(méi)有表面上的主語(yǔ)，但它所表達(dá)的意義是動(dòng)作，這一動(dòng)作的執(zhí)行者就是該動(dòng)詞的邏輯主語(yǔ)，動(dòng)詞不定式要和它的邏輯主語(yǔ)在語(yǔ)態(tài)和時(shí)態(tài)上保持一致。
動(dòng)詞不定式的用法
1.不定式作主語(yǔ)
⑴原則上，可用動(dòng)詞不定式直接作句子的主語(yǔ)，通常用it作句子的形式主語(yǔ)，而把不定式移到后面，形成“It + 謂語(yǔ)… + 動(dòng)詞不定式…”的句型。如：
To catch the 5：00 bus early in the morning is not a good idea. It is not a good idea to catch the 5：00 bus early in the morning. To learn a foreign language well takes painstaking efforts. It takes painstaking efforts to learn a foreign language well.⑵若要說(shuō)明不定式的動(dòng)作的執(zhí)行者，可以在不定式前面加上“for + 名詞或代詞”結(jié)構(gòu)，或是“of + 名詞或代詞”結(jié)構(gòu)。
It is a great pleasure for me to talk with him. It is very kind of you to help me .⑶可用于“of + 名詞/代詞 + 動(dòng)詞不定式”結(jié)構(gòu)中作主語(yǔ)補(bǔ)足語(yǔ)的形容詞是指那些可以表示人或事物的性質(zhì)或品質(zhì)的好壞的形容詞。這些詞如：careful， cruel， foolish， bold， brave， good， honest， kind， rude， polite， nice，stupid， selfish， silly， wicked， wise， thoughtful， wrong等。
2.不定式作賓語(yǔ)
不定式作賓語(yǔ)有兩種情況：一是及物動(dòng)詞后直接跟帶to的不定式，二是“動(dòng)詞+疑問(wèn)詞+帶to的不定式”。
⑴“動(dòng)詞+帶to的不定式”結(jié)構(gòu)：常見(jiàn)的以不定式作賓語(yǔ)的動(dòng)詞有afford， appear， agree， ask， believe， decide， demand， desire， fail， hope， intend，learn， mean， offer， promise，refuse， wish等。如：
I can‘t afford to buy a house.⑵“動(dòng)詞+疑問(wèn)代(副)詞+不定式”結(jié)構(gòu)：常見(jiàn)的這類動(dòng)詞有advise， decide， forget， know， learn， remember， see， tell， think， teach， wonder，discover， understand， guess， explain等。這類疑問(wèn)代(副)詞what， when， which， where， how， whether等(不包含why)。如：
She does not know how to go there. He will tell you how to deal with it.⑶在不定式作賓語(yǔ)時(shí)，有時(shí)我們會(huì)使用it作形式賓語(yǔ)，而把不定式放到后面。如：
They consider it inappropriate to have classes in the evening.
3.不定式作表語(yǔ)
不定式作表語(yǔ)時(shí)，主語(yǔ)通常是一個(gè)名詞，不定式短語(yǔ)或者從句。
The boss‘s plan is to start building the skyscraper immediately. To work means to earn a living. What you have to do is to push the button.
4.不定式作定語(yǔ)
不定式作定語(yǔ)相當(dāng)于一個(gè)定語(yǔ)從句，它修飾以下幾類名詞：
⑴由動(dòng)詞派生或轉(zhuǎn)化而來(lái)的名詞，它們所對(duì)應(yīng)的動(dòng)詞通常有不定式作賓語(yǔ)。
Another attempt to climb the mountain will be made next month. In his speech he expressed his determination to achieve the goal.這類名詞主要有：attempt， claim， decision， plan， promise， intention， need，resolution，tendency， wish， failure， threat等。
⑵由可能與不定式搭配的形容詞派生出來(lái)的名詞。
Her eagerness to learn a foreign language obvious.這類名詞主要有：anxiety， patience， ability， willingness， ambition等。
⑶不定式作定語(yǔ)還可用來(lái)修飾代詞something， anything， everything， nothing. She has everything to lose and nothing to gain.⑷由only， last， next， 序數(shù)詞或形容詞級(jí)修飾的名詞后常用不定式作定語(yǔ)。Jim is the only student to answer the question correctly in his class. You are the last to undertake the blood test.⑸不定式常作為定語(yǔ)修飾there be結(jié)構(gòu)的真實(shí)主語(yǔ)。
There is a big task to complete.⑹ 有些抽象名詞。主要有：reason， right， time， effort， chance， way等。如： the time to go to school， the way to get to the clinic， the chance to win the game.
5.不定式作狀語(yǔ)
不定式作狀語(yǔ)相當(dāng)于一個(gè)狀語(yǔ)從句，表示形為的目的、結(jié)果或原因。
⑴表示目的。在這種情況下，不定式的邏輯主語(yǔ)通常也是全句的主語(yǔ)。
He stayed there to see what would happen.在強(qiáng)調(diào)不定式目的狀語(yǔ)時(shí)，不定式前可加in order， so as等。如：
She asked me to drive her to the airport in order to catch the 5：00 plane. He moved the TV set to the meeting-room so as to let everyone watch it.
⑵用so……as to……， such (……) as to……， enough to……， too……to， only to等表示結(jié)果，如：
Have you got enough room to seat all of us?
She is too weak to join us in the outing.
⑶將不定式移到句首表示條件，如：
To hear the teacher better， you have to sit in the front. = If you are to hear the teacher better，……
⑷與形容詞連用時(shí)，大多表示原因。這些形容詞主要有：happy， kind， surprised， frightened， angry， shocked， glad， delighted， grieved，disappointed等。
They were surprised to be informed of the news. I‘m glad to hear this.
動(dòng)詞不定式指由to加上動(dòng)詞原形所構(gòu)成的一種非限定性動(dòng)詞，但在有些情況下to 可省略。動(dòng)詞不定式在語(yǔ)法功能上可作主語(yǔ)、賓語(yǔ)、表語(yǔ)、定語(yǔ)和狀語(yǔ)，如：
To ignore this dangerous signal would be a terrible mistake. (作主語(yǔ))
He promised not to tell anyone else about it. (作賓語(yǔ))
To treat comrades like enemies is to go over to the side of the enemy.(作表語(yǔ))
The manager announced his intention to retire.(作定語(yǔ))
The old man walked slowly on the ice in order not to fall down.(作狀語(yǔ))
不定式中的動(dòng)詞仍然具有動(dòng)詞的特性，可以有自己的賓語(yǔ)和狀語(yǔ)，另外雖然動(dòng)詞不定式在語(yǔ)法上沒(méi)有表面上的主語(yǔ)，但它所表達(dá)的意義是動(dòng)作，這一動(dòng)作的執(zhí)行者就是該動(dòng)詞的邏輯主語(yǔ)，動(dòng)詞不定式要和它的邏輯主語(yǔ)在語(yǔ)態(tài)和時(shí)態(tài)上保持一致。
動(dòng)詞不定式的用法
1.不定式作主語(yǔ)
⑴原則上，可用動(dòng)詞不定式直接作句子的主語(yǔ)，通常用it作句子的形式主語(yǔ)，而把不定式移到后面，形成“It + 謂語(yǔ)… + 動(dòng)詞不定式…”的句型。如：
To catch the 5：00 bus early in the morning is not a good idea. It is not a good idea to catch the 5：00 bus early in the morning. To learn a foreign language well takes painstaking efforts. It takes painstaking efforts to learn a foreign language well.⑵若要說(shuō)明不定式的動(dòng)作的執(zhí)行者，可以在不定式前面加上“for + 名詞或代詞”結(jié)構(gòu)，或是“of + 名詞或代詞”結(jié)構(gòu)。
It is a great pleasure for me to talk with him. It is very kind of you to help me .⑶可用于“of + 名詞/代詞 + 動(dòng)詞不定式”結(jié)構(gòu)中作主語(yǔ)補(bǔ)足語(yǔ)的形容詞是指那些可以表示人或事物的性質(zhì)或品質(zhì)的好壞的形容詞。這些詞如：careful， cruel， foolish， bold， brave， good， honest， kind， rude， polite， nice，stupid， selfish， silly， wicked， wise， thoughtful， wrong等。
2.不定式作賓語(yǔ)
不定式作賓語(yǔ)有兩種情況：一是及物動(dòng)詞后直接跟帶to的不定式，二是“動(dòng)詞+疑問(wèn)詞+帶to的不定式”。
⑴“動(dòng)詞+帶to的不定式”結(jié)構(gòu)：常見(jiàn)的以不定式作賓語(yǔ)的動(dòng)詞有afford， appear， agree， ask， believe， decide， demand， desire， fail， hope， intend，learn， mean， offer， promise，refuse， wish等。如：
I can‘t afford to buy a house.⑵“動(dòng)詞+疑問(wèn)代(副)詞+不定式”結(jié)構(gòu)：常見(jiàn)的這類動(dòng)詞有advise， decide， forget， know， learn， remember， see， tell， think， teach， wonder，discover， understand， guess， explain等。這類疑問(wèn)代(副)詞what， when， which， where， how， whether等(不包含why)。如：
She does not know how to go there. He will tell you how to deal with it.⑶在不定式作賓語(yǔ)時(shí)，有時(shí)我們會(huì)使用it作形式賓語(yǔ)，而把不定式放到后面。如：
They consider it inappropriate to have classes in the evening.
3.不定式作表語(yǔ)
不定式作表語(yǔ)時(shí)，主語(yǔ)通常是一個(gè)名詞，不定式短語(yǔ)或者從句。
The boss‘s plan is to start building the skyscraper immediately. To work means to earn a living. What you have to do is to push the button.
4.不定式作定語(yǔ)
不定式作定語(yǔ)相當(dāng)于一個(gè)定語(yǔ)從句，它修飾以下幾類名詞：
⑴由動(dòng)詞派生或轉(zhuǎn)化而來(lái)的名詞，它們所對(duì)應(yīng)的動(dòng)詞通常有不定式作賓語(yǔ)。
Another attempt to climb the mountain will be made next month. In his speech he expressed his determination to achieve the goal.這類名詞主要有：attempt， claim， decision， plan， promise， intention， need，resolution，tendency， wish， failure， threat等。
⑵由可能與不定式搭配的形容詞派生出來(lái)的名詞。
Her eagerness to learn a foreign language obvious.這類名詞主要有：anxiety， patience， ability， willingness， ambition等。
⑶不定式作定語(yǔ)還可用來(lái)修飾代詞something， anything， everything， nothing. She has everything to lose and nothing to gain.⑷由only， last， next， 序數(shù)詞或形容詞級(jí)修飾的名詞后常用不定式作定語(yǔ)。Jim is the only student to answer the question correctly in his class. You are the last to undertake the blood test.⑸不定式常作為定語(yǔ)修飾there be結(jié)構(gòu)的真實(shí)主語(yǔ)。
There is a big task to complete.⑹ 有些抽象名詞。主要有：reason， right， time， effort， chance， way等。如： the time to go to school， the way to get to the clinic， the chance to win the game.
5.不定式作狀語(yǔ)
不定式作狀語(yǔ)相當(dāng)于一個(gè)狀語(yǔ)從句，表示形為的目的、結(jié)果或原因。
⑴表示目的。在這種情況下，不定式的邏輯主語(yǔ)通常也是全句的主語(yǔ)。
He stayed there to see what would happen.在強(qiáng)調(diào)不定式目的狀語(yǔ)時(shí)，不定式前可加in order， so as等。如：
She asked me to drive her to the airport in order to catch the 5：00 plane. He moved the TV set to the meeting-room so as to let everyone watch it.
⑵用so……as to……， such (……) as to……， enough to……， too……to， only to等表示結(jié)果，如：
Have you got enough room to seat all of us?
She is too weak to join us in the outing.
⑶將不定式移到句首表示條件，如：
To hear the teacher better， you have to sit in the front. = If you are to hear the teacher better，……
⑷與形容詞連用時(shí)，大多表示原因。這些形容詞主要有：happy， kind， surprised， frightened， angry， shocked， glad， delighted， grieved，disappointed等。
They were surprised to be informed of the news. I‘m glad to hear this.