情態動詞
can , could , may , might , must , shall , will , would , need , dare , dared , should , ought to , used to; had better; would rather
情態動詞表猜測
1) should / ought to 照說應該，估計 The photo should be ready by 12 o’clock .
2) may / might / must / can’t / couldn’t 表猜測，
a.非常肯定的猜測
must “肯定, 一定” can’t “肯定不,不可能”He must be at home now.
He must like English. He can’t be at home now.
He can’t have much money.
注意: mustn’t “不準,禁止”You mustn’t talk in class.
b.表示不太肯定的猜測： may/might 可能 may not, might not 可能不
can/could 只用于疑問句和否定句中
You may not remember me. I thought he might remember me.
---Can it be true.? --- No, it can’t true.
could/might 表示過去，但也可表示現在，表示現在時，它的可能性比can/ may要小。
He may/might be in Class One .
注意1：表猜測時，時態體現在情態動詞后面
a.對過去的猜測-情態動詞后面用完成時
1 He must have read books about Shakespeare because he knows so much about him.
2 -- I called him last night, but nobody answered.
--He can’t /couldn’t have been at home.
3 In those days I may have been pretty.
b.對現在的猜測 ---情態動詞后面用動詞原形或進行式。
1 He can’t like this kind of book.
2 They may be playing football now.
注意2 :a。may / might / must / can’t / couldn’t 表猜測時的反意疑問句。
He might have a lot of work to do now , doesn’t he ?
He may have missed the early bus , hasn’t he ?
I must have been asleep when you rang me , wasn’t I ?
It can’t rain tomorrow , will it ?
He must be studying in the classroom now , isn’t he ?
b．can 表猜測一般用于否定句或疑問句中，在肯定句中往往表示“一時的可能性”
“有時可能會”
Training by yourself can be highly dangerous .
二）情態動詞表虛擬
could have done 本可以-----
may/might have done 本來可能---
should / ought to have done 本來應該---- shouldn’t/ought not to have done本不該---
needn’t have done 本不必----
wouldn’t have done 本不會---
1 Chuck also learns that he should have cared more about his friends .
2 You needn’t have come here so early.
3.You needn’t have gone there yesterday .
4.We ought to have given you more help , but we were so busy .
5.We could have walked to the station , it was so near .
****三）幾組詞的區別
1）can , be able to a.. can 只有現在式和過去式，而be able to 有各種時態，
b. can 表能力，be able to 表成功地完成某一具體動作，相當于manage to do ,succeed in doing
Below the 11th floor people were able to escape .
2) must , have to have to “必須，不得不”表客觀需要
must 表說話人的主觀看法
3）would , used to 兩者都可以表示過去的習慣。但would表示過去反復發生的動作或過
去的一種傾向，現在可能還存在，而used to表示現在不復存在的過去的狀態、情況和動
作。
Often he would hear a long low whistle and the sound of a metallic noise .
I used to have an old jeep .
** 注意的否定和疑問句，
Used you to go to the same school ? = Did you use to go to the same school ?
I usedn’t to smoke . = I didn’t use to smoke .
4) need , dare 作為情態動詞，一般用于否定句，疑問句，條件句中(除 I dare say ----)，
沒有人稱和數的變化，否定句在其后加not ，疑問句把need , dare ,dared 提前，后面接
動詞原形。***除了在I dare say---這種習慣用語中
---If you die ,who will get your money?----I dare say my uncle will.
而作為及物動詞時，有人稱、數和時態的變化，否定句，疑問句要借助于助動詞do ,
does ,did 。跟不定式作賓語。
She dare not say what she thinks . = She doesn’t dare to say what she thinks .
You don’t need to read the book if you don’t want to.
5)will 1）表示說話時做出某種決定時. ---- The phone is ringing . ----- I’ll answer it .
2) 表示一種傾向、習慣性動作或說話人的揣測的意見。
Without water flowers will die . After supper, he will have tea.
6).shall 1）用于第一人稱，表示將來，
2）用于第一、三人稱，在問句中表示征求別人的意見或向對方請示
-----Shall he wait outside or come in ?
3）用于第二、三人稱，表示說話人對對方的命令、警告、允諾、威脅、決心。
He shall have the book when I finish reading .