Question

should have done;must have done;need have done;could have done的区别是什么？

Answer 1

一、
“must+have+done”表示对过去事情的肯定推测，译成“一定做过某事”，该结构只用于肯定句。
1.
It
must
have
rained
last
night,
for
the
ground
is
wet.
昨晚一定下雨了，因为地面还是湿的。
2.
You
must
have
been
mad
to
speak
to
the
servant.
你和仆人说话，一定是发疯了。
二、
“can't+have+done”表示对过去事情的否定推测，译成“不可能做过某事”。
1.
Mr.
Smith
can't
have
gone
to
Beijing,
for
I
saw
him
in
the
library
just
now.
史密斯先生不可能去北京了，我刚才还在图书馆见过他。
2.
Mary
can't
have
stolen
your
money.
She
has
gone
home.
玛丽不可能偷你的钱，她回家去了。
三、
“can+have+done”表示对过去行为的怀疑，用于疑问句，译成“可能做过……吗？”。
1.
There
is
no
light
in
the
room.
Can
they
have
gone
out?
屋里没有灯，他们可能出去了吗？
2.
There
is
nowhere
to
find
them.
Where
can
they
have
gone?
到处找不到他们，他们可能到什么地方去呢？
四、
“could+have+done”是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做。
He
could
have
passed
the
exam,
but
he
was
too
careless.
本来他能够通过考试，但是他太粗心。
五、
“may+have+done”表示对发生过的事情的推测，意思是“可能已经”或“也许已经”，用于肯定句中。
—What
has
happened
to
George?
—I
don't
know.
He
may
have
got
lost.
—乔治发生了什么事？
——我不知道，他可能迷路了。
六、
“might+have+done”表示对过去事情的推测，might与may意思相同，但可能性更小。多用于虚拟语气结构中。
1.
He
might
have
given
you
more
help,
even
though
he
was
busy.
他或许会多给你一些帮助，即使他很忙。
2.
She
might
have
achieved
greater
progress,
if
you
had
given
her
more
chances.
如果你多给她点机会，她可能已经取得更大的成绩。
七、
“would+have+done”虚拟语气，表示对过去事情的假设，意思是“本来会做”。
1.
I
would
have
told
you
all
about
the
boy's
story,
but
you
didn't
ask
me.
我本来会告诉你这个小男孩的故事，但是你没有问我。
2.
Without
your
help,
I
wouldn't
have
achieved
so
much.
没有你的帮助，我是不会取得如此大的成绩。
八、
“should+have+done”意思是“本来应该做某事，而实际没做。”
“shouldn't+have+done”表示本来不应该做某事，而实际做了。含有指责对方或自责的含意。
1.
Tom,
you
are
too
lazy.
The
work
should
have
been
finished
yesterday.
汤姆，你太懒惰了，这项工作本来应该昨天就做完的。
2.
Look,
Tom
is
crying.
I
shouldn't
have
been
so
harsh
on
him.
看，汤姆哭了，我本来不应该对他如此严厉。
十、
“need+have+done”表示本来需要做某事而没有做。“needn't+have+done”则表示“本来不需要做某事而做了”。
I
needn't
have
bought
so
much
wine—only
five
people
came.
我本来没有必要买这么多酒，只来了五个人。