開學啦！開學啦！！吾日三省吾身：功課預習了嗎？新學期你準備好了嗎？一起來看看高二英語語法知識點總結！
高二英語語法知識點總結：不定式的用法
動詞不定式具有名詞、形容詞和副詞的特徵。因此在句中可以做主語、表語、賓語、賓語補足語、定語和狀語。
一、不定式做主語：
1、不定式做主語一般表示具體的某次動作。===動名詞doing 表示習慣的，經常的動作。
e.g: To finish the building in a month is difficult.
To do such things is foolish.
To see is to believe. (對等)
注: 1). 不定式作主語時,謂語用單數
2). 當主語較長，謂語較短時，常用it做形式主語，而將不定式放到謂語的後面。
it做形式主語，不定式放在謂語動詞之後常用於下列結構中：
(1)It is/was +adj.+of sb. to do…
(2) It is +adj.+for sb.+to do…
It is easy / difficult / hard / foolish / unwise / right / wrong / unnecessary
(3) it is +a +名詞+ to do...
It is a pity / a pleasure / a pleasant thing / one’s duty / an honor / a shame / a crime / no easy job… to do
It takes (sb.) some time / courage / patience …to do…
It requires courage / patience / hard work… to do…
*注意: probable 和 possible 均可作表語，但possible可以用不定式作真實主語， 而probable不能用不定式作真實主語。
It is probable for him to come to the meeting.(錯)
It is possible for him to come to the meeting.
It is possible / probable that he will come to the meeting.
二、不定式做表語
主語是以aim duty hope idea intention plan job suggestion wish purpose task 等為中心詞的名詞詞組 或以 what 引導的名詞性從句表示，後面的不定式說明其內容, 不定式作表語常表示將來或現在的動作或狀態。
eg :My idea is to climb the mountain from the north.
Your mistake was not to write that letter.
What I would suggest is to start work at once.
三、動詞不定式作賓語
以不定式結構為賓語的動詞有：
ask, agree, care, choose, demand, decide, expect, fail, help, hope, learn, manage, offer, plan, prepare, pretend, promise, refuse, want, wish等只能用動詞不定式作賓語
口訣(接不定式作賓語的動詞)
想要學習 早打算( want learn plan)
快準備 有希望( prepare hope wish expect)
同意否 供選擇(agree offer choose)
決定了 已答應(decide be determined promise)
盡力去 著手做(manage undertake)
別拒絕 別假裝(refuse pretend)
失敗不是屬於你(fail)
e.g.Tom refused to lend me his pen.
We hope to get there before dark.
The girl decided to do it herself.
*注意:某些及物動詞可用-ing也可用動詞不定式作賓語但意義不同的有
stop go on remember forget
regret try mean can’t help
be used to