情态动词can和could的用法

ability 能力
obligation
义务, 责任
certainty 确定性
permission 允许
make requests
提出请求
make suggestions 提出建议
make offers
提供帮忙
give
提出忠告
advice
用法一：Ability (能力)
Liu Xiang can run the 110m
• The fire spread through the hotel very quickly but everyone _D___ get out.
A .had to
B. would
C. could
D. was able to
be able to do sth. = manage to do sth. = succeed in doing sth.
3. I’m sorry I h_a_v_e_n_’_t _b_e_e_n a_b_l_e_t_o( 不能） play tennis with you recently.
4. It’s nice to ___b_e_a_b_l_e _t_o___(能）attend the lecture.
5. Wang Gong _m__ig_h_t_b_e_ a_b_l_e_ t_o__ (可能能） win the chess game.
could 常用于疑问句中，
No , you mustn’t . 比can 更加委婉，表示礼貌。
Please don’t . 用于回答时，常用原形can
No ,you may not. 或者may ,不可再用过去式
could或might
用法三.Making requests (提出要求)
I don’t know how to use this equipment!
quite well, but a few years ago, wew_e_r_e_n_’_t(a不b能le to
be able to 也可表示能力，它的用法， 要比can/could要正式一些, 但不常用。
can/be able to区别:
Edison always wondered why hens could hatch (孵) chickens
be able to 1.用于不同的时态 2. 可用在不定式之后 3. 可用在情态动词之后
试试吧！
They will ___D___ run this machine on their own in three months. A. can B. could C. may D. be able to
while he was not able to.
Question: Are the two modal verbs interchangeable (互换) ? If not, why?
can表示与生俱来的能力或一种客观可能，而 be able to更加强调通过后天的学习和努力获 得的能力，或者在某个客观的场合和背景下， 能做到的事情。
hurdle race within 13 seconds.
1.Now many of us __c_a_n_(能） speak English quite
well, but a few years ago, wec_o_u__ld_n_’t (不能 • can指现在的能力 • could表示过去的能力 2.Now many of us a_r_e__a_ble t(o能）speak English
B. can’t but do sth= have no choice but to do sth= can’t choose but do sth= have to do sth 不得不做某事
C .can’t help to do sth= can’t help do sth. 不能帮忙做某事 can’t wait to do sth. 迫不及待做某事 can’t help doing sth. 情不自禁做某事 can’t help but do sth. 忍不住做某事。 can’t afford to do sth. 不能承担得起做某事 can’t tell A and/from B 不能区分A和B
Finish the exercises about the workbook on P49
Check the answers:
1. A 2. B 3. A 4. D 5. A 6. B
wenku.baidu.com
Homework
• preview the modal verbs: • may/might • must • shall
A must B can C should D would
That big cinema __A____ seat 2,000 people.
A.can B. should C. ought to D. is able to
用法五：can/could:
1.表示惊异、怀疑、不相信的态度。（主 要用在否定句、疑问句或惊叹句中）
（肯定句 对将来的推测）
2）He couldn’t/can’t have enough money for a new car.( 否定句，对现在的推测）
3）He couldn’t /can’t be singing.（否定句，对 进行的推测)
4) Could/Can he have heard the news ?(疑问句， 对过去的推测）
2. Finish the relevant exercises.
• Self-study guidance (1 )
• Refer to the workbook on P49 and find out the definition of modal verbs and consider how many modal verbs you know.
4) Could he have heard the news ? (对过去的推测）
very uncertain
almost certain
might may could should ought to will
can 推测（表示可能）一般只用于否定句和疑问 句，而could一般无此限制。
1）We could go there this summer.
A
用法二：表示允许（permission)
---Can/Could I have a look at your new pen ? ---Yes ,you can/ No , you can’t.
---Could I borrow your dictionary ?
---Yes , of course you _C__
用法四 could 用于表示的推测（表示可能） 1）We could go there this summer.
（对将来的推测） 2）He couldn’t have enough money for a new
car now. ( 对现在的推测） 3）He couldn’t be singing. （对进行的推测)
• could推测的语气比can推测的语气较弱 • can推测的把握性很大。
• can表示理论上或是逻辑上判断的可能性， 一般翻译成“会”。常用在肯定句中
It is usually warm in my hometown in March, but it _B___ be rather cold sometimes.
• Lead-in
• We can be there on time tomorrow. • May I come in ? • Shall we begin now? • You must obey the school rules.
Learning objectives
1.Master basic usage of modal verbs ( can/could).
情态动词的定义:
• 情态动词是一种本身有一定的词义,表示说话人 的情绪,态度或语气的动词,但不能单独作谓 语, 只能和其他动词原形构成谓语。
How many modal verbs do you know?
can could may might shall should must will would ought to
Can you help me with my training?
make requests
will / can / could / would
informal
formal
—Will / Can/ Could/Would you help me with my training?
—Yes, I will/can/can/will.
A might B will C can D could
Permission 允许
can / could / may / might
informal / spoken
formal / written
Can/May/Could/Might I come in?
Yes , you can/may
Yes ,please.
Can this be true?
He’s such a nice person that
he _c_a_n_’_t_ commit the crime.
你Ho怎w么ca会n 如yo此u b地e粗so心c！areless!
Why/How + should/can 结构表示说 话人对某事不能理解，感到意外、惊 异。“竟会”。
• Why should you be so late today ？
• How can you be so careless?
其他惯用法
A. can’t/can never… too…= can’t/ can never…enough 无论怎么…也不为过…
越…越好。
You can’t be too careful when crossing the street.
1.--- How’s your new babysitter(保姆) ?（2011） ---We __D__ ask for a better one. All our kids
love her so much. A. should B. might C. mustn’t D. couldn’t 2.Mary __B__ be in Paris , for I saw her in the town only a few minutes ago. A mustn’t B can’t C shouldn’t D may not
have to
dare (daren’t)
need (needn’t)
used to
modal verbs
•
• can/could 的 用法
Modal verbs: general introduction
二．情态动词的语法功能
We can use modal verbs to talk about: