学英语，只有在死记的基础上才能活用。背诵就是死记的第一步。背诵以背小短文为好。背诵的好处很多，可以使我们熟悉英语的词汇和结构，增强语感。以下是小编给大家整理的高二英语选修七第一课知识点总结，希望能助你一臂之力!
高二英语选修七第一课知识点总结1
一、不定式做主语：
1、不定式做主语一般表示具体的某次动作。===动名词doing 表示习惯的，经常的动作。
e.g: To finish the building in a month is difficult.
To do such things is foolish.
To see is to believe. (对等)
注: 1). 不定式作主语时,谓语用单数
2). 当主语较长，谓语较短时，常用it做形式主语，而将不定式放到谓语的后面。
it做形式主语，不定式放在谓语动词之后常用于下列结构中：
(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 +名词+ 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 均可作表语，但possible可以用不定式作真实主语， 而probable不能用不定式作真实主语。
It is probable for him to come to the meeting.(错)
It is possible for him to come to the meeting.
It is possible / probable that he will come to the meeting.
二、不定式做表语
主语是以aim duty hope idea intention plan job suggestion wish purpose task 等为中心词的名词词组 或以 what 引导的名词性从句表示，后面的不定式说明其内容, 不定式作表语常表示将来或现在的动作或状态。
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、动词不定式作宾语
以不定式结构为宾语的动词有：
ask, agree, care, choose, demand, decide, expect, fail, help, hope, learn, manage, offer, plan, prepare, pretend, promise, refuse, want, wish等只能用动词不定式作宾语
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