中考复习情态动词课件(共27张PPT)

(共27张PPT)
情态动词
什么是情态动词？
·有一定的词义，但不能单独作谓语，必须和行为动词
或系动词连用，构成谓语。
·无人称和数的变化（除have to区别）
·具有助动词的作用，可用来构成否定句，疑问句及
用于简明答语。
·后加动词原形
头脑风暴
----快速说出你知道的情态动词！
情态动词
表示推测
can
may
must
表
示
义
务
should
must
have to
need
表示能力
can
could
表
示
建议
had better
should
一、表示推测类
She must dislike such a man.
How can that be true
The woman in the picture may be her sister.
must表示肯定是，用于肯定句
can 表示可能，用于否定句，疑问句
may表示可能，用于肯定句
对一般现在推测 对现在进行推测 对一般过去推测 对过去进行推测
“肯定是”
“不可能是”
“可能是”
must be
can’t be
may be
must be doing
can’t be doing
may be doing
must have done
can’t have done
may have done
must have been doing
can’t have been doing
may have been doing
两个特殊记忆点：
You mustn’t smoke in the hospital.
Must I finish the homework now
--Yes, you must. /Yes, you have to.
--No, you needn’t. /No, you don’t have to.
mustn’t表示禁止。
回答Must疑问句，肯定用must；否定用needn’t 或don’t have to.
May I come in now
--Yes, you may. /Yes, you can.
--No, you mustn’t. /No, you can’t.
may表示请求时，肯定回答用may，can；否定回答用mustn’t 或can’t。
二、表示义务类
Students must finish their homework before class.
I have to go now.
Children should learn to respect others.
I need type this letter before work.
I need to type this letter before work.
must:必须
have to: 不得不
should：应该
need：需要
need 需要（情态动词、实意动词）
have to 不得不
三、表示能力类
I can draw. = I am able to draw.
I could ride a bike when I was six years old.
can:能，可以，相当于be able to
四、表示建议类
You should see a dentist.
You had better not go there by air. =You’d better not…
should:应该
had better:最好
五、几组容易混淆的词
must vs. have to
I must brush my teeth before going to bed.
I have to go to see the doctor.
must 强调说话者的主观意愿，无人称，时态的变化；mustn’t表示禁止；
have to强调客观上的必要性，常翻译为“不得不”，有人称和时态的变化。
can vs. be able to
She can sing the song.
Some of the singers were able to sing English songs
as well as native speakers.
can表示能力，许可，建议，请求和可能性。只有can, could两种形式。
be able to表示在具体某件事上的能力，其形式主要靠be动词来变化，形式比can多。
ought to vs. should
Every citizen ought to perform military service.
You should not run alongside the swimming pool.
ought to侧重于表示按照法律，法规等规定，就强制意义的责任或义务。
should含有个人意见，强调主观看法，语气比ought to稍弱。
had better
It’s raining outside, you’d better stay at home.
It’s very cold, you had better not go out.
had better+动词原形，否定形式用had better not+do，表示最好……
maybe VS. may be
She may be Lily’s mother.
Maybe I’ll come back in three days.
may 为情态动词后加be形成了推测；
maybe是副词，意思为“大概，也许”，相当于perhaps，用于句首。
need VS. need
I need to type this letter before three o’clock.
I need clean my bedroom now.
need后加to do，说明need是实意动词，用助动词变句式；
need后加do，说明是情态动词，在need上变句式。
dare VS. dare
Most people hate Harry but they don't dare to say so.
Dare she risk staying where she was
dare后加to do，说明dare是实意动词，用助动词变句式；
dare后加do，说明是情态动词，在dare上变句式。
写出下列情态动词的过去式
can
may
must
shall
will
need
could
might
should
would
needed
would, should, could, might等过去式有时不表示过去，而是表示更委婉客气的语气。
分类练习
can
may
must
shall
will
need
have to
had better
should
ought to
be able to
能，可能，应该，
必须，不得不，需要
最好，将要，可以