八年级英语上册 Unit 9 Can you come to my party语法

Unit 9 Canyou come to my party?
单元语法聚焦九
情态动词can, have to的用法
【正面阐述】
1．can的用法
can是一个情态动词，其后接动词原形，其否定形式是_____，它的过去式为_____ ，否定形式为_____。

can的用法如下：
注意：can表示请求或用于发出邀请时，如果接受对方的邀请时常用“Sure，I'd love (like) to. /Certain- ly. /Of course.”等回答；如不接受，常用sorry等有礼貌地拒绝，但一般情况下需要说明不能接受邀请的原因并表示歉意。

如：
—Can you come to my birthday party tomor- row?
明天你能来参加我的生日聚会吗？
—Sorry, I can't. I'm going to visit my grandpa.
对不起，我不能去。

我打算去看望我爷爷。

2．have to的用法
3．have to与must的区别
(1) have to意为“不得不，必须”，它强调一种客观情况。

must意为“必须”，着重于说话人主观上认为“有义务，有必要”。

如：
We have to pay a fine.
我们不得不交罚款。

You must do it yourself．
你必须自己做。

(2)have to有单复数及时态的变化，must无人称、时态、数的变化。

如：
She has to finish her homework.
她必须完成作业。

She must finish her homework.
她必须完成作业。

(3)过去时及将来时的句子常用have to，而不用must。

They had to send him to his home.
他们不得不送他回家。

She had to do some washing yesterday.
昨天她不得不洗衣服。

答案
1．can't could couldn't
2．has to had to do
【反面解读】
1．人称和数的误用
误：He cans swim.
正：He can swim.
2．时态的误用
误：He can play the piano when he was eight years old.
正：He could play the piano when he was eight years old.
3．情态动词的误用
误：We have to obey the traffic rules.
正：We must obey the traffic rules.
【实战演练】
()1.—Can you stay here for lunch?
—Sorry,_____ .I have to see my par- ents.
A.I can't
B.I shouldn't
C.I mustn't
D.I don't
()2. —I can't stop playing computer games.
—For your health, my boy, I'm afraid you____．
A. can
B. must
C. have to
D. may
()3. —Could you please close the door?
—Yes, I_____.
A.can
B.must
C.could
D.should
()4. —Can you play the piano?
—Yes, I_____. I often practice it on weekends.
A needn't B. need C. can't D. can
( )5.Who's the man over there? Is it MrBlack?
-It_____ be him. He's much taller.
A can't B. mustn't C. should D. may
( )6.— Mr Wang, must I come again on Sun-day morning to clean the windows? —No, you_____ .I have asked others to do it．
A.don't have to
B.mustn't
C.can't
D.shouldn't
答案
1-6 ACADAA。