内容正文：
Unit 2
I’ll help to clean up the city parks.
Section A GF-4c
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Learning objectives
1.正确使用我们在本单元学习的短语动词；
2.判断不定式的不同词性及用法；
3.知道如何正确使用不定式作为句子中不同的功能成分
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Free talk
Do you want to be a volunteer?
What kind of volunteer work do you think you could do?
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I’d like to help homeless people. She decided to try out for a volunteer after-school reading program.
You could ask hospitals to let you visit the kids and cheer them up. Mario believes it can help him to get his future dream job.
She volunteers there once a week to help kids learn to read. I’m making some signs to put up around the school.
I’d like to do
ask sb. to do
volunteer…to do
learn to do
decide to do
help sb. to do
make…to do
let sb. do
help sb. do
Grammar Focus
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动词不定式
动词不定式是一种非谓语动词形式，在句中不能作谓语，没有人称和数的变化。
基本形式：to＋动词原形，有时to可以省略；否定形式：not + 动词不定式。
动词不定式具有名词、形容词和副词的特征，因此可以在句中作主语、宾语、宾语补足语、定语和状语等。
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常接动词不定式作宾语的动词有：
想要 拒绝 忘记 (want, refuse, forget)
需要 努力 学习 (need, try, learn)
选择 同意 帮助 (choose, agree, help)
希望 决定 开始 (hope/wish/expect, decide, begin/start)
Lily wants to find a job as an English teacher in Beijing.
He decided to help the homeless.
动词不定式作宾语
动词不定式的用法
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常接动词不定式作宾补的动词有：
ask, tell, want, teach, wish, help, warn, invite, encourage 等可以构成“...sb. (not) to do sth.”结构的动词。
Sam asked me to help him.
The teacher always tells us not to swim in the river.
动词不定式作宾语补足语
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在let, make, see, watch, hear, feel, notice, have等感官听觉动词或使役动词后面作宾语补足语的动词, 其不定式一般要省略动词不定式符号“to”。
let / make / have + sb. + do sth.
see / watch / hear / notice / feel + sb. + do sth.
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动词不定式作状语
1）作目的状语。强调动词不定式所表示的目的时，动词不定式
可用in order to或so as to +动词原形，so as to不用于句首。
e.g. The bus stopped so as to pick up passengers.
2）作结果状语。
e.g. He woke up only to find everybody gone.
His grandma lived to see the liberation of China.
He is old enough to go to school.
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3）在某些表示喜、怒、哀、乐等的形容词后作原因状语
e.g. I’m proud to have taken part in the competitions.
She was surprised to see him.
They jumped for joy to hear the news.
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