备战2018高考英语一轮复习专题讲解（词法部分）情态动词

情态动词
情态动词顾名思义就是表示情感和态度的词，常见的有：can
(could);
may
(might);
must;
have
to;
shall
(should);
will
(would);
need;
dare
(dared);
ought
to;
情态动词没有人称和数的变化，不能单独使用，它与其后的动词原形合成谓语结构。它们的用法如下：
can和could
的用法
表示能力或客观的可能性，还可以表示请求和允许。如：
Can
you
finish
this
work
tonight
Man
cannot
live
without
air.
—
Can
I
go
now
—
Yes,
you
can.
注意：
could表示语气较委婉的请求，主要用语疑问句，（用于此意义时不用在肯定句）答语用can。
—
Could
I
come
to
see
you
tomorrow
—
Yes,
you
can.
(不能用could).
（否定句常用No,
I'm
afraid
not.）
can表示能力时，还可以用
“be
able
to”
代替，例如：
I'll
be
able
to
come
this
afternoon.
但当我们要表示“某件事已成”时，须用
“was
(were)
able
to”不能用could，例如：
He
was
able
to
go
to
the
party
yesterday
evening
and
he
enjoyed
himself
very
much.
表示“惊异、怀疑、不相信”的态度。（主要用在否定句、疑问句和感叹句中）
Can
this
be
true
How
can
you
say
like
that
This
cannot
be
done
by
him.
“can
(could)
+
have
+
done”
的疑问或否定形式表示对过去发生的行为怀疑或不肯定。
He
cannot
have
been
to
that
town.
Can
he
have
got
the
book
may
和might
的用法
表示许可，表示请求、允许时，might
比may
的语气更加委婉一些，否定回答时可用can’t
或mustn’t,
表示“不可以、禁止、阻止”之意。
例如：
—
Might
I
use
your
pen
—
No,
you
mustn’t.
—
May
I
take
this
book
out
—
Yes,
you
can
(—
No,
you
can’t/
mustn’t.)
用May
I…
征询对方许可在文体上较正式，在口气上比较客气，在日常口语中，用Can
I…
征询对方意见在现代口语中更为常见。
用于表示祝愿的句子中。例如：
May
you
success!
May
you
be
happy!
May
you
have
a
good
journey!
表示推测、可能（疑问句中不用于此意）
He
may
be
very
busy
now.
(此句中用might
语气较弱)
“May
(Might)
+
have
+
done”
表示对过去发生的行为的推测。例如：
He
may
not
have
finished
the
work.
(此句中用might
语气较更弱)
must
和
have
to
的用法
表示“必须、必要”。
You
must
come
on
time.
当must
引出的问句时，
若是否定的回答，不能用mustn’t，而用needn’t或don’t
have
to.
—
Must
we
hand
in
our
exercise
our
books
today
—
Yes,
you
must.
(No,
needn’t/you
don’t
have
to.)
“must
be
+
表语”的结构表示推测，它的否定或疑问形式用can
代替must。如：
He
must
be
our
new
teacher.
Can
he
be
our
new
teacher
He
can’t
be
our
new
teacher.
※
附加疑问句要和谓语动词实际时态一致。如：
He
must
be
our
new
teacher,
isn’t
he
“must
+
have
+done”
的结构常用在肯定句中，表示对过去或完成的情况推测，它的否定或疑问形式也用can代替must.
He
must
have
finished
his
work.
※
附加疑问句也要和谓语动词实际时态一致。如：
He
must
have
finished
his
work
already,
hasn’t
he
He
must
have
finished
his
work
at
four
yesterday,
didn’t
he
have
to
的含义与must相似，两者往往可以互换使用，但have
to有各种形式，随have的变化而定，must
与have
to有下列几点不同：
must表示的是说话人的主观看法，而have
to则往往强调客观需要，例如：
The
play
is
not
interesting.
I
really
must
go
now.
I
had
to
work
when
I
was
your
age.
两者的否定意义大不相同。例如：
You
mustn’t
go.
(你不可以去)
You
don’t
have
to
go.
(你不必去)
询问对方的意见时应用must。
Must
I
hand
in
the
exercise
book
before
eight
must
表示“偏偏”
Must
it
rain
today
（今天怎么偏偏下雨呢？）
dare
和need的用法
need表示“需要，必须”，作情态动词时，仅用于疑问句和否定句，在肯定句中一般用must,
have
to,
ought
to,或should代替。例如：
You
needn’t
come
so
early.
—
Need
I
clean
all
the
room
right
now
—
Yes,
you
must.
(—
No,
you
needn’t.)
注意：needn’t
+
have
+done表示“本来不必要做的事而实际上做了”，例如：
You
needn’t
have
waited
for
me.
你本来没有必要等我的。
dare作情态动词时，主要用于疑问句，否定句和条件句中，一般不用于肯定句，例如：
How
dare
you
take
my
book
without
permission
He
dare
not
speak
English
before
such
a
crowd,
dare
he
need和dare作情态动词时，过去时形式与现在形式相同（美国英语中可用dared）。
He
was
so
angry
that
no
one
dared
say
a
word.
They
said
that
he
needn’t
stay
there
any
longer.
need和dare常用实义动词，有时态、人称和数的变化。不同的是dare作实义动词时，在肯定句中通常接带to的不定式，在疑问句和否定句中，dare之后的不定式可带to或不带to。例如：
He
needs
to
finish
the
work
before
nightfall.
I
dare
to
swim
across
this
river.
He
does
not
dare
(to)
answer
the
teacher’s
question.
Don’t
you
dare
(to)
touch
it
I
wonder
he
dared
say
that.
I
dare
say是习惯用语，常可写为I
daresay，用法有以下几种：
“敢于说”，通常接that或what引导的名词性从句。
I
dare
say
that
he
has
stolen
Tom’s
football.
I
dare
say
what
I
think.
“我想；恐怕；大概；也许是”，通常作插入语用，使句子委婉。
I
dare
say
there
is
something
wrong
with
the
machines.
You’re
tired,
I
dare
say.
You,
I
dare
say,
think
otherwise.
I
dare
say往往也作为反语使用。
Oh,
you
mean
to
defeat
our
football
team
I
dare
say
you
will.
（噢！你们想赢我们的足球队？也许可以吧。）
shall和should的用法。
shall用于第一人称疑问句。表示征求对方意见。
What
shall
we
do
this
evening
Shall
I
open
the
window
shall
用语第三人称疑问句中，表示说话人征求对方的意见或向对方请示。
When
shall
he
be
able
to
leave
the
hospital
shall用于第二、三人称的陈述句，表示说话人给对方的“命令、警告、允诺或威胁”。
You
shall
fail
if
you
don’t
work
harder.
He
shall
have
the
book
when
I
finish
reading.
He
shall
be
punished.
should表示劝告、建议、命令，其同义词是ought
to，在疑问句中，通常用should代替ought
to.
You
should
go
to
class
right
away.
Should
I
open
the
window
should
+
have
+done应该做的事实上没做；shouldn’t
have
done不该做的事却已经做了，常含有责备的意思。
You
should
have
started
earlier
this
morning.
You
shouldn’t
have
treated
her
like
that.
will和would的用法。
用于疑问句表示请求、建议等，would比will的语气更加委婉。
Will
you
please
give
me
a
hand
Would
you
mind
my
smoking
here
表示意志、愿望和决心。
I
will
never
do
that
again.
They
asked
us
if
we
would
do
that
again.
用“will
be”和“will
have
done”的结构表示推测，主要用于二、三人称，前者表示对目前的情况的推测，后者表示对已经完成的动作或事态的推测。
This
will
be
the
book
you
want.
He
will
have
arrived
by
now.
would可表示过去反复发生的动作或某种倾向，表示过去习惯时比used
to正式，同时它没有“现在已无此习惯”的含义。
I
would
visit
him
during
my
vacation.
The
patient
would
not
recover.
表示料想或猜想。
He
would
be
your
new
teacher.
He
would
not
come
any
more.
ought
to的用法。
ought
to表示应该时意义与should基本一致，但更侧重于一种义务或责任。
You
ought
to
take
care
of
him.
Parents
ought
to
bring
up
their
children.
表示推测，注意与must表示推测时的区别。
He
must
be
home
by
now.
He
ought
to
be
home
by
now.
This
is
where
she
must
be.
This
is
where
she
ought
to
be.
ought
to
have
done的用法与should
have
done的用法相同
注意：ought
to在美国英语中，用于否定句和疑问句时，to可以省略。如：
Ought
you
smoke
so
much
You
oughtn’t
smoke
so
much.
used
to;
had
better;
would
rather的用法。
used
to表示过去习惯动作或状态，现在已经不存在，在间接引语中，其形式可不变。如：He
told
us
he
used
to
play
football
when
he
was
young.
在疑问句、否定句或否定疑问句中，可有两种形式。
疑问句：Did
you
used
to/Used
you
to
go
to
the
same
school
as
your
brother
否定句：I
usedn’t
to/didn’t
use
to
go
there.
(usedn’t
也可为usen’t,
发音不变)。
否定句疑问句：Usedn’t
you
to/Didn’t
you
used
to
be
interested
in
the
play
在附加疑问句和简略答语中，也可有两种形式。
She
used
to
be
very
fat,
didn’t/usedn’t
she
—
Did
you
used
to/Used
you
to
play
chess
—
Yes,
I
did/used
to.
had
better意为“最好”，后接不带to不定式。
We
had
better
go
now.
Hadn’t
we
better
stop
now
I
think
I’d
better
be
going.
You
had
better
have
done
that.
would
rather意为“宁愿”，表示选择，后接不带to的不定式。
I’d
rather
not
say
anything.
Would
you
rather
work
on
a
farm
—
Wouldn’t
you
rather
stay
here
—
No,
I
would
not.
I’d
rather
go
there.
由于would
rather表选择，故后面可接than.
I
would
rather
watch
TV
than
go
to
see
than
go
to
see
the
film.
I
would
rather
throw
it
away
than
you
should
get
it.（若than后面接从句常用should
do）
I’d
rather
you
didn’t
talk
about
this
to
anyone.
※
would
rather
还可写为would
sooner/would
as
soon.
专项训练
单项选择
—
Must
we
do
it
now
—
No,
you________.
A.
won’t
B.
needn’t
C.
can’t
D.
don’t
You________
to
the
meeting
this
afternoon
if
you
have
something
important
to
do.
A.
needn’t
to
come
B.
don’t
need
come
C.
don’t
need
coming
D.
needn’t
come
—
May
I
pick
a
flower
in
the
garden
—
________.
A.
No,
you
needn’t
B.
Not,
please
C.
No,
you
mustn’t
D.
No,
you
won’t
—
Can
I
leave
this
door
open
at
night
—
You________
better
not.
A.
should.
B.would
C.
could
D.
had
Put
on
more
clothes.
You________
be
feeling
cold
with
only
a
shirt
on.
A.
can
B.
could
C.
would
D.
must
I
thought
you________
like
something
to
read,
so
I
have
brought
you
some
books.
A.
may
B.
might
C.
could
D.
must
There
was
plenty
of
time.
She________.
A.
mustn’t
have
hurried
B.
couldn’t
have
hurried
C.
must
not
hurry
D.
needn’t
have
hurried
Where
is
my
pen
I
________
it.
A.
might
lose
B.
would
have
lost
C.
should
have
lost
D.
must
have
lost
I
didn’t
hear
the
phone.
I________
asleep.
A.
must
be
B.
must
have
been
C.
should
be
D.
should
have
been
He
________
you
more
help,
even
though
he
was
very
busy.
A.
might
have
given
B.
might
give
C.
may
have
given
D.
may
give
A
computer
________
think
for
itself;
it
must
be
told
what
to
do.
A.
can’t
B.
couldn’t
C.
may
not
D.
might
not
—
Shall
we
go
skating
or
stay
at
home
—
Which
________
do
yourself
A.
do
you
rather
B.
would
you
rather
C.
will
you
rather
D.
should
you
rather
Tom
ought
not
to________
me
your
secret,
but
he
meant
no
harm.
A.
have
told
B.
tell
C.
is
telling
D.
having
told
—
Don’t
forget
to
come
top
my
birthday
party
tomorrow.
—
________.
A.
I
don’t
B.
I
won’t
C.
I
can’t
D.
I
haven’t
It
nearly
seven
o’clock.
Jack________
be
here
at
any
moment.
A.
must
B.
need
C.
should
D.
can
—
Can
I
help
you,
sir
—
Yes.
I
bought
this
radio
here
yesterday,
but
it________.
A.
didn’t
work
B.
won’t
work
C.
can’t
work
D.
doesn’t
work
The
fire
spread
through
the
hotel
very
quickly
but
everyone________
get
out.
A.
had
to
B.
would
C.
could
D.
was
able
to
—
When
can
I
come
for
the
photos
I
need
them
tomorrow
afternoon.
—
They________
be
ready
by
12:00.
A.
can
B.
should
C.
might
D.
need
—
Will
you
stay
for
lunch
—
Sorry,________.
My
brother
is
coming
to
see
me.
A.
I
mustn’t
B.
I
can’t
C.
I
needn’t
D.
I
won’t
—
Are
you
coming
to
Jeff’s
party
—
I’m
not
sure.
I________
go
to
the
concert
instead
A.
must
B.
would
C.
should
D.
might
I
was
really
anxious
about
you.
You________
home
without
a
word.
A.
mustn’t
leave
B.
shouldn’t
have
left
C.
couldn’t
have
left
D.
needn’t
leave
—
Is
John
coming
by
train
—
He
should,
but
he
________
not.
He
likes
driving
his
car.
A.
must
B.
can
C.
need
D.
may
A
left-luggage
office
is
a
place
where
bags
________
be
left
for
a
short
time,
especially
at
a
railway
station.
A.
should
B.
can
C.
must
D.
will
I’ll
do
all
I
________
help
you.
A.
can
B.
can
to
C.
am
able
to
D.
could
Who________
it
be
that
has
left
the
book
on
my
desk
A.
must
B.
shall
C.
may
D.
can
I
wish
to
take
a
walk
with
you,
________
A.
will
you
B.
shall
we
C.
may
I
D.
shall
I
Robots________
a
lot
of
work
in
place
of
us.
A.
are
used
to
do
B.
used
to
do
C.
are
used
to
doing
D.
used
to
doing
He
must
have
suffered
a
great
deal
from
the
Great
Cultural
Revolution,________
he
A.
mustn’t
B.
needn’t
C.
didn’t
D.
hasn’t
You
oughtn’t
to
have
done
wrong
to
him,________
you
A.
ought
B.
will
C.
ought
to
D.
did
It’s
very
late.
You________
go
home
now.
A.
had
better
B.
would
like
to
C.
would
rather
D.
would
sooner