高中英語詞法專題情態動詞精品教案
英語詞法專題講座十：情態動詞一.情態動詞的用法
1. can 用法
1）表示能力，與be able to同義，但can只用于現在時和過去時，be able to可用于各種時態。
two eyes can see more than one.
注：can you … ? yes, i can / no, i can’t.
2). 表示允許、請求
用could比can 語氣更加委婉客氣，常用于could i /you …..? 句型中，若表示同意時，用can回答而不用could.
could i borrow the book ? no, you can’t.
3). 表示推測 “可能”常用于否定句或疑問句中。（can’t表示一定不是）
it can’t be true.
can it be true?
2. may 用法
1）表允許，請求= can
表示許可或征求對方的許可，常于第一人稱連用。
注：may i ….? yes, you may. no, you can’t / mustn’t.
在回答以may引起的問句時，多避免用這個詞，而用其它方式，如yes, please. / certainly.
2）表推測，可能、也許。常用于肯定句中。
maybe he knows the news. =
he _____ _____ the news.
3. must
1）表示義務。意為“必須”（主觀意志）。
we must do everything step by step.
注：must i ….? yes, you must / no, you needn’t (don’t have to ).
--must we hand in our exercise—books now?
--no, you needn’t. / no, you don’t have to.
2）mustn’t 表禁止、不允許。
you mustn’t talk to her like that.
3）表示揣測。意為“想必、準是、一定”等，只用于肯定句。否定、疑問句中must改為can.
he must be ill. he looks so pale.
she’s wearing a diamond necklace. she must have a lot of money.
注：must表推測時，其反義疑問句與must后面的動詞一致。
there must be something wrong, ____ ____?
4. need的用法
need既可用作情態動詞，也可用作實義動詞。用作情態動詞時，主要否定句或疑問句中。用作實義動詞時，可用于各種句式。
1). 用作情態動詞，用于否定句和疑問句中。
a). need i ….? yes, you must / no, you needn’t .
need we finish the work today ? yes you __?
a. need b. can c. may d. must
b). need + do sth . 變否定句：needn’t do sth
變疑問句：need sb do sth ?
2). 用作實義動詞
a). need + to do sth . we need _______(buy) some school things .
變否定句：don’t /doesn’t /didn’t +need to do sth .
變疑問句：do / does /did sb + need to sth ?
yes , … do/ does / did no, sb don’t / doesn’t /didn’t.
you don’t need to do it yourself.
b). 當主語是物時。sth + need + doing sth = sth +need to be done .
the table needs painting. =the table needs _____ _____ _____ .
5. had better 的用法
1). had better + 動詞原形 = it’s best to do sth.
you had better ______ (stay )at home. = _____ ______ ______ stay at home.
2). had better not +動詞原形
we had better ________(not play ) the computer games.