情态动词can的用法
一、基本用法
1.表示能力(如体力和脑力方面),意为“能;会”等。例如:
Canyou speak English? 你会讲英语吗?
Canyou play the piano? 你会弹钢琴吗?
2.表示请求或允许,多用在口语中,意为“可以;能”等。用于疑问句中用来提出要求,用于否定句表示不允许。例如:
CanI help you? 我能帮助你吗?
Youcan’t play basketball.
你不能玩篮球。
Canyou...?“请你……好吗?”表示说话人的请求;
CanI...?“我可以……吗?”用来征求对方是否允许自己做某事。如在句末加上please一词就显得更有礼貌了。
例如:
Canyou help me, please? 请你帮助我好吗?
3.表示可能。例如:
Hecan be at home now. 他现在可能在家。
Themoon can’t always be full. 月亮不可能常圆。
4.表示怀疑。在表达此意时,只能用于一般疑问句中,带有感情色彩。例如:
Canit be true? 那会是真的吗?
二、句式变化如下:
1.在变否定句时,直接在can后加上“not”,可缩写成can’t或cannot,但不能写成cann’t。例如:
Hecan swim. → He can’t swim.
Tonycan see the pen on the desk.→ Tony cannot see the pen on the desk.
在变一般疑问句时,直接移到主语前(原主语的首字母改成小写,第一人称应变为第二人称)即可。例如:
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Ican see an orange on the table. → Canyou see an orange on the table?
其回答可用Yes,OK或Certainly等作肯定回答;用No或Sorry等作否定回答。例如:
—Canyou look after my dog, please? 你能照看一下我的狗吗?
—OK.可以。
用Certainly回答。此时语气更为肯定。
—CanI see your piano? 我能看看你的钢琴吗?
—Certainly.当然可以。
1.can和could表示能力
(1)can表示现在的能力,也表示将来的能力,could 表示过去的能力。例如:
I can’t speakFrench. But I can speak English.
我不会说法语,但我会说英语。
She could play thepiano when she was only six.
她六岁的时候就会弹钢琴了。
(2)can表示能力时与be able to do sth的意思相同;值得注意的是,can只有现在时和过去时两种时态,而be able to do sth可以用于各种时态。例如:
Look! I can do it.看,我能做它。
They are able tosing these English songs.他们能唱那些英语歌曲。
At that time Icould still read without glasses.
那个时候,我仍然可以不戴眼镜看书。
2. can, could和may表示许可
(1) can表达许可。表达许可基本上可分为“请求”和“准许”两种。例如:
—Can I use yourtelephone? 我可以借用你的电话吗?
—Yes, of courseyou can.可以呀,当然可以。
(2) could表达许可比can来的更加委婉。例如:
—Could/Can I useyour pen? 我可以借用你的钢笔吗?
—Yes, of courseyou can.当然可以。(不能说Yes, you could.)
(3) may表达许可。例如:
May I come in? 我可以进来吗?
注意:can和may都可表示“准许、请求,许可”,此时两兄弟同义,可以互换使用。不过在这方面用may比用can好一些,因为在表示“请求”时,may表现的更谦虚,更委婉一些。例如:
You can/may gohome with your mother now. 现在你可以和妈妈一块回家了。
语法练习
一、单项选择 (10分)
1.She is very old, ______she canstill look after herself.
A. but
B. because
C. unless
D. if
2. —Come on, let’s______!
—I just want to take it easy. Myfeet are killing me.
A. study
B. chat
C. dance
D. listen
3.—______your brother speak Japanese?
—Yes, he has learnt it in Tokyo for three years.
A. Should
B. Must
C. Can
D. May
4. —Listen, the music _______ sweet.
—It’s Yesterday Once More, my favorite.
A. sounds
B. smells
C. feels
D. looks
5.After school, I had a long_______ with my teacher about my study.
A. talk
B. word
C. speech
D. story
6. I can play the guitar, but I_______ play the violin.
A. don’t
B. am not
C. can’t
D. mustn’t
7.—______ is her favorite subject?
—Her favorite subject is art.
A. Why
B. When
C. Who
D. What
( )8. Tom can play _______ tennis butcan’t play ________ guitar.
A.the, the
B. /, /
C.the, /
D./ , the
( )9.Miss King isgood ________music.She can be good _______ children in the music club.
A.at, at
B.with, with
C.at, with
D.with, at
( )10.________ he can ________ our school play.
A.Maybe, in
B.Maybe, be in
C.May be, in
D.May be, be in
二、在B栏中选择A栏的答句.(10分)
A B
( )1. Can he sing or dance? A. Yes, I am.
( )2. Are you playing computer? B. He can dance.
( )3. What club do you want to join?C. Yes, I can.
( )4. Can you sing well? D. Sounds great.
( )5. Let’s tell stories after class. E. Mus