動(dòng)詞不定式具有名詞、形容詞和副詞的作用,它可以作主語(yǔ)、賓語(yǔ)、賓補(bǔ)和狀語(yǔ).
(1)作主語(yǔ)
動(dòng)詞不定式作主語(yǔ)時(shí),常用it作形式主語(yǔ),而將真正的主語(yǔ)放在句末,It＋be＋形容詞＋(for sb)＋動(dòng)詞不定式.
It's important (for us) to protect environment.
(對(duì)我們來(lái)說(shuō))保護(hù)環(huán)境是很重要的.
注：當(dāng)在kind,good,nice,clever等表示人的品質(zhì)的形容詞后,不用for而用of.
It's very kind of_you_to_help_me.
你幫助我真是太好啦.
It's very clever of_you_to_do_like_that.
你那樣做真是太聰明啦!
(2)作賓語(yǔ)
He wants to_go_out_with_her.
注：①一些謂語(yǔ)動(dòng)詞后只能用不定式作賓語(yǔ),常見(jiàn)的這類(lèi)詞表示命令、打算或希望,如：would like,want,wish,hope,decide,plan,expect等.
Would you like to_see_a_film this evening?
你今晚想去看電影嗎?
②在find,think后跟不定式作賓語(yǔ)時(shí),常用it代替,而將真正的賓語(yǔ)放在句末.
I find it easy to_read_English_every_day.
我發(fā)現(xiàn)每天讀英語(yǔ)很容易.
(3)賓語(yǔ)補(bǔ)足語(yǔ)
動(dòng)詞不定式作賓補(bǔ)時(shí),它與賓語(yǔ)有邏輯上的主謂關(guān)系.
Lucy asked him to_turn_down_the_radio.
露西要他關(guān)小收音機(jī).
(4)作定語(yǔ)
動(dòng)詞不定式作定語(yǔ)時(shí),應(yīng)放在名詞之后,它與名詞有邏輯上的動(dòng)賓關(guān)系.
I have a lot of homework to_do.
我有許多家庭作業(yè)要做.
There is nothing to_worry_about.
沒(méi)什么要擔(dān)心的.
(5)作狀語(yǔ)
Mrs Wang went to Shanghai to_see_her_daughter.(目的)
王太太去上海看她女兒.
We're glad to_meet_you here.(原因)
我們很高興在這見(jiàn)到你.
He is too tired to_work_on.(結(jié)果)
他太累了而不能繼續(xù)工作.
3．不定式的否定形式是在不定式前加not.
They told us not_to_play basketball too long.
他們告訴我們不要玩太長(zhǎng)時(shí)間籃球.
You'd better not_go_to_bed late.
你最好不要睡覺(jué)太晚.
4．不定式常和疑問(wèn)詞what,which,when,where,how連用,相當(dāng)于一個(gè)賓語(yǔ)從句.
The teacher is telling the students what_to_do.
老師正告訴同學(xué)們做什么.
He didn't know where_to_go.(where to go＝where he should go)
他不知道去哪里