不定式是非謂語動詞的一種，也是我們現(xiàn)階段英語學(xué)習(xí)的重點。不定式到底有哪些用法呢？讓我們從一些題目中來看一看吧。

用法一：作主語

It？蒺s standard practice for a company like this one a security officer.

A.employed B.being employed C.to employ D.employs

解析 本題考查固定句型：It+be+n+for sb./sth. to do...，考點為不定式作主語，故答案為C。

對不定式作主語的考查，常常以固定句型的形式出現(xiàn)，主要有以下5種句型：

①It+be+名詞+to do...

e.g.：It？蒺s our duty to take good care of the old.

②It+be+形容詞+for sb.+to do...

e.g.：It is difficult for us to finish the task in an hour.

③It+be+形容詞+of sb.+to do...

e.g.：It is stupid of you to write down everything the teacher says.

④It takes sb.+some time+to do...

e.g.：How long did it take you to finish the work？

⑤It seems+形容詞+to do...

e.g.：It seemed impossible to save money.

只要熟記這些句型，不定式作主語的題目就能迎刃而解了。

用法二：作賓語

1.David threatened his neighbor to the police if the damage were not paid.

A.to be reported B.reporting C.to report D.having reported.

2.Susan wanted to be independent of her parents.She tried alone，but she didn？蒺t like it and moved back home.

A.living B.to live C.to be living D.having lived

解析 1.考查不定式作賓語。threatened的后面只能接不定式作賓語，句中表示“大衛(wèi)威脅鄰居如果損害沒有得到賠償，他將報警”。故答案為C。

考點分析：下列動詞后面只能接不定式作賓語：決心學(xué)會想希望，設(shè)法拒絕愿假裝，主動答應(yīng)選計劃，同意請求幫一幫。這一順口溜對應(yīng)下列單詞：decide/determine，learn，want，hope/wish/expect ，manage，refuse，care，pretend，offer，promise，choose，plan，agree，ask/beg，help。我們記住了這個順口溜，做題的時候就能事半功倍了。

2.考查不定式和動名詞作賓語時的區(qū)別。此時要注意區(qū)分：try doing 意為“嘗試做……”， 而try to do 意為”努力去做…… ”。根據(jù)句意“蘇珊不想再依靠父母，她嘗試獨自居住但并不喜歡 ，最后又搬回了家”確定答案為 A。類似的詞還有can？蒺t help，go on，mean，forget，remember，regret，stop 及try，要注意他們后面跟動名詞和不定式時意義上的區(qū)別。

牛刀小試：

1.The boy pretended when his motherentered.

A .reading B.to read C.to be reading D.being read

2.Nervous and anxious ，Jill failed a good impression at the job interview.

A.to have made B.making C.to make D.having made

3.We find it impossible for the work ahead of time.

A.to finish B.finishing C.being finished D.to be finished

4.—What about your adventure in the forest last week？

—Wonderful！I didn？蒺t expect there so many lovely monkeys！

A.to be B.being C.of being D.be

答案 1.C 2.A 3.D 4.A

用法三：作表語

Ladies and gentlemen，please remain until the plane has come to a complete stop.

A.seated B.seating C.to seat D.seat

解析 不定式作表語?？疾橄祫釉~remain后面的情況。remain作“尚待，留待”講時，后加“to be done”作表語；remain作“仍然”時，后面加現(xiàn)在分詞或過去分詞作表語。因此答案為B。

用法四：作定語

1.There are still many problems before we are ready for a long stay on the Moon.

A.solving B.solved C.being solved D.to be solved

2.The airport next year will help promote tourism in this area.

A.being completed B.to be completed C.completed D.having been completed

不定式作后置定語時，修飾前面的名詞或代詞，表示不定式動作尚未發(fā)生或?qū)⒁M行。

解析 1.在there be 結(jié)構(gòu)中，當(dāng)說話人強調(diào)的是必須有人去完成某件事情時，不定式用主動形式；如果說話人強調(diào)的是事情本身必須被完成，不定式則用被動形式。本題題意為“在我們準備在月球上長期生活之前，還有很多問題有待于解決?！狈治鼍渥咏Y(jié)構(gòu)得知，空處在句中作定語。又根據(jù)語境可知此處表示沒有發(fā)生的事情，應(yīng)用不定式，又因為solve和problems之間為動賓關(guān)系，因此用不定式的被動式，故選擇D。

2.分析句子結(jié)構(gòu)得知，空處在句中作定語。又根據(jù)語境可知此處表示沒有發(fā)生的事情，應(yīng)用不定式，又因為complete和airport之間為動賓關(guān)系，因此用不定式的被動式，故選擇B。

牛刀小試：

1.The pressure causes Americans to be energetic，but it also puts them under a constant emotional strain.

A.to compete B.to be competed C.competing D.having competed

2.Could you find someone ？

A.for me to play tennis with B.for me to play tennis

C.play tennis with D.playing tennis

3.With a lot of difficult problems ，the newly-elected president is having a hard time.

A.settled B.settling C.to settle D.being settled

答案 1.A 2.A 3.C

用法五：作狀語

1.Group activities will be organized after class children develop team spirit.

A.helping B.having helped C.helped D.to help

2. ourselves from the physical and mental tensions，we each need deep thought and inner quietness.

A.Having freed B.Freed C.To free D.Freeing

解析 1.分析句子可知道這里需要目的狀語，句意為“為了幫助孩子們培養(yǎng)團隊精神，下課后將組織小組活動”。目的狀語通常用不定式表示。故選擇D。

2.根據(jù)題干和句意可知本題考查不定式作目的狀語，相對于上一題，本題結(jié)構(gòu)更清晰。句意為“為了讓我們從身體和精神的緊張中放松下來，我們都需要深刻的思考和內(nèi)心的平靜。”故選擇C。綜合這兩題，我們得出結(jié)論：目的狀語通常用動詞不定式表示。

牛刀小試：

1.George returned after the war，only that his wife had left him.

A.to be told B.telling C.being told D.told

2.The air is very hard to in Tibet because of the high altitude.

A.breath in B.be breathed in C.breath D.be breathed

答案 1.A 2.C

用法六：作補語

Ⅰ.作賓語補足語

1.I advised him smoking ，but he wouldn？蒺t listen.

A.give up B.to give up C.giving up D.to be given up

2.Whom would you like with you，John or me？

A.go B.have gone C.have go D.to go

解析 這兩題考查一些動詞后面用動詞不定式作賓語補足語的情況。常見的結(jié)構(gòu)為：advise/allow/ask/expect/encourage/get/invite/like/persuade/remind/require/suppose/tell/want/warn/wish/would like/call on/depend on+sb.+（not） to do sth.。故第1題選擇B，第2題選擇D。

Ⅱ.作主語補足語

1.Passengers are permitted only one piece of hand luggage onto the plane.

A.to carry B.carrying C.to be carried D.being carried

2.He is thought foolishly.Now he has no one but himself to blame for losing the job.

A.to act B.to have acted C.acting D.having acted

解析 主語補足語的出現(xiàn)是因為原來含有賓語補足語的句子變成了被動句，因此，原來的賓語就變成了新句子的主語，那么原來的賓語補足語就變成了新句子的主語補足語了。因此，我們做題的時候只要將結(jié)構(gòu)還原成原來的主動句就可以了。

1.分析題目知道句意是“旅客僅被允許攜帶一件手提行李上飛機”，permit sb. to do sth.結(jié)構(gòu)變成被動為sb.be permitted to do sth.，因此選項為A。

2.本題考查sb./sth. be said/believed/known/supposed/reported/considered/found/thought...+to do sth./to be done/to have done/to have been done，本結(jié)構(gòu)中，用to do表示尚未發(fā)生的動作，用to have done表示已經(jīng)發(fā)生的動作。根據(jù)句意“他被認為表現(xiàn)得很愚蠢”，表示已經(jīng)發(fā)生了的動作，故選擇B。

牛刀小試：

1.They knew her very well.They had seen her up from childhood.

A.grow B.grew C.was growing D.to grow

2.The teacher asked us so much noise.

A.don？蒺t make B.not make C.not making D.not to make

3.My advisor encouraged a summer course to improve my writing skills.

A.for me taking B.me taking C.for me to take D.me to take

4.The flu is believed by viruses that like to reproduce in the cells inside the human nose and throat.

A.causing B.being caused C.to be caused D.to have caused

5.—Is Bob still performing？

—I？蒺m afraid not.He is said the stage already as he has become an official.

A.to have left B.to leave C.to have been left D.to be left

答案 1.A 2.D 3.D 4.C 5.A