must
必须,应该,一定,准是,
表示说话人认为有必要做某事,
命令,
要求别人做某事以及对事物的推测。
must
用来指一般现在时和一般将来时,
过去式可用
have
to
的过去式代替。
i
must
finish
my
work
today.
我今天必须完成我的工作。
you
mustn't
work
all
the
time.
你不能老是工作。
must
i
return
the
book
tomorrow?
我必须明天还书吗?
after
such
a
long
walk,
you
must
be
tired.
走了这么长的路,你一定困了。
he
must
be
the
man
i
am
looking
for.
他一定是我要找的人。
he
had
to
go
because
of
somebody's
calling
him
that
day.
那天他要走是因为有人叫他。
must
+
have
+
过去分词,表示现在对过去事物的推测。
he
must
have
told
my
parents
about
it.
他一定把这件事情告诉我父母亲了。
he
must
have
received
my
letter
now.
他现在一定收到我的信了。
it's
six
o'clock
already,
we
must
have
been
late
again.
已经六点钟了，我们一定又迟到了。
must
和
have
to
的区别:
must
表示说话人的主观思想,
have
to
表示客观需要。
you
must
do
it
now.
你必需现在就干。(说话人认为必须现在干)
i
have
to
go
now.
我得走了。(客观条件必须现在走)
need
需要
多用在否定式或疑问句中.
need
i
attend
the
meeting
tomorrow?
我需要明天参加会议吗?
you
need
not
hand
in
the
paper
this
week.
这一周你不必交论文。
need
是一个情态动词,
他的用法完全和其他情态动词一样,
但
need
还可当作实义动词使用,
这时
need
就象其他动词一样,有第三人称,单复数,
后面加带
to
的动词等特性。
i
need
a
bike
to
go
to
school.
我上学需要一辆自行车。
do
you
need
a
dictionary?
你需要词典吗?
she
needs
a
necklace.
她需要一条项链。
needn't
+
have
+
过去分词
表示过去做了没必要做的事情。
you
needn't
have
taken
it
seriously.
这件事情你不必太认真。
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