人教版八年級(jí)英語下冊(cè)《I'll help to clean up the city parks》SectionA PPT教學(xué)課件(第3課時(shí))，共32頁。
Objectives
To learn the use of infinitives.
To learn to express your intentions to be a volunteer.
Grammar Focus
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.
動(dòng)詞不定式
動(dòng)詞不定式是一種非謂語動(dòng)詞形式，在句中不能作謂語，沒有人稱和數(shù)的變化。
基本形式：to＋動(dòng)詞原形，有時(shí)to可以省略；否定形式：not＋動(dòng)詞不定式。
動(dòng)詞不定式具有名詞、形容詞和副詞的特征，因此可以在句中作主語、賓語、賓語補(bǔ)足語、定語和狀語等。
一、作賓語
動(dòng)詞不定式（短語）可以放在一些動(dòng)詞后面
用作賓語，能以動(dòng)詞不定式作賓語的動(dòng)詞有：
begin, want, remember, agree, learn, like, decide, fail, pretend, demand, refuse等。
二、 作賓語補(bǔ)足語
動(dòng)詞不定式作賓語補(bǔ)足語，表示賓語所做的動(dòng)作，可以用動(dòng)詞不定式作賓語補(bǔ)足語的動(dòng)詞有：tell, ask, want, like, invite, encourage, help等。如：
The teacher asked us to read English for half an hour in the morning.
The teacher often tells Jim not to spend too much time playing computer games.
Please let me help you.
但在let, make, see, watch, hear, feel, notice, have等感官聽覺動(dòng)詞或使役動(dòng)詞后面作賓語補(bǔ)足語的動(dòng)詞, 其不定式一般要省略動(dòng)詞不定式符號(hào)“to”，可以歸納為以下三種句式：
1.不可以省略to的不定式作賓語補(bǔ)足語: tell /ask / want / would like / wish /
suppose / invite /encourage /teach/ depend on等 + sb.+ to do sth.
例如：
The teacher told us to come earlier.
Her success encouraged me to try the same thing.
Her parents wish her to be a teacher.
2.省略“to”的不定式作賓語補(bǔ)足語：
let / make / have + sb. +do sth. 例如：
Let the girl leave here now.
The boy made the baby cry.
see / watch / hear / notice / feel +sb.+do sth.
例如：
I saw the students play basketball on the playground yesterday.
I often hear the girl sing in the next room.
3.可省可不省的: help sb. （to）do sth.
例如：
I often help my mother (to) do housework.
三. 作狀語:
（1）作目的狀語。強(qiáng)調(diào)動(dòng)詞不定式所表示的目的時(shí)，動(dòng)詞不定式可用in order to或so as to +動(dòng)詞原形，so as to不用于句首。
例如：
He stopped to have a rest.
The bus stopped so as to pick up passengers.
（2）作結(jié)果狀語。
例如：
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.
（3）在某些表示喜、怒、哀、樂等的形容詞后作原因狀語。例如：
I’m proud to have taken part in the competitions.
I’m happy to have found many things I can do.
動(dòng)詞不定式的否定形式：
（1）動(dòng)詞不定式的否定式是直接在to之前加not. 如：
Tell them not to play football in the street.
（2）省略to的動(dòng)詞不定式的否定式是直接在動(dòng)詞前面加not. 如：
Let the boy not go.
Homework
Review the grammar points we learn today. Make some sentences with infinitives.
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