你提出来的是同一论题的不同的方面，下面分两方面作答:
一、含蓄条件句:
所谓含蓄条件句就是利用语境不直接说出条件的句子。这种句子可以分为两类:一种是广义的含蓄条件句，另一种是狭义的含蓄条件句。
1.
广义含蓄指的是不用连词
if
或
unless
介绍条件，而是改用其他方式。事实上这些表达方式也是同样是条件状语。
(1)用介词引入条件:
*
but
for(如不是,
如没有):注意，凡是出现这个复合介词的句子，必须要用虚拟语气，如:
We
would
have
had
a
pleasant
journey
but
for
the
rain.(=
We
would
have
had
a
pleasant
journey
if
it
hadn’t
rained.)
*
without/with
(在不具备/具备…的条件下),
如:
Without
his
help,
I
could
not
have
done
it
well.
(=If
he
hadn’t
helped
me,
I
could
not
have
done
it
well.)
With
favorable
winds,
we
might
have
got
there
in
tow
days.
(=
If
there
should
be
favorable
winds,
we
might
have
got
there
in
tow
days.)
*
under
(在…条件下)
We
could
have
done
better
under
more
favorable
conditions.
(=
We
could
have
done
better
if
we
were
to
be
under
more
favorable
conditions.)
(2)分词短语充当条件(分词短语本身就具有充当条件状语的功能)，如:
Given
a
certain
oppertunity,
he
could
have
shown
more
talent.
(=
If
he
hade
been
given
a
certain
oppertunity,
he
could
have
shown
more
talent.)
(3)表示不具备条件的连词连词:but,but
that,or或otherwise不定式短语
They
would
have
resisted
but
that
they
lacked
courage.
(=
They
would
have
resisted
if
they
hadn’t
lacked
courage.
要不是缺乏勇气她们会抵抗的.
)
诸如此类，不一而足。
2.
狭义含蓄指的是不用任何语言方式显示条件，而是把条件隐藏在具体的原环境中，
(1)用上下文暗示条件，如:
I
was
so
busy
then,
otherwise,
I
would
have
finished
it.
(If
I
hadn’t
been
busy
then,
I
would
have
finished
it.)
It
rained
yesterday,
or
I
would
have
gone
camping.
(If
It
hadn’t
rained
yesterday,
I
would
have
gone
camping.)
(2)用委婉语气暗示条件，如:
Would
you
mind
opening
the
window?
(=Would
mind
if
I
opend
the
window.)
Could
you
do
me
a
favour
to
pass
me
the
book?
(=
You
would
do
me
a
favour
if
you
should
pass
me
the
book.
)
(3)用表示愿望的语气暗示条件，如:
Long
live
the
Chairman
Mao!
(=
If
Chairman
Mao
should
live
long.)
(4)用其他语言环境暗示条件，如:
That
would
be
fine.
(
=省略了If
you
should
do
it.)
You
might
saty
here
forever.
(=省略了
If
you
wanted
to.)
I
would
not
have
done
it.
(=省略了
If
I
were
you.)
二、含蓄条件句的虚拟时间
含蓄条件句是一种不出现条件从句的句子，也就是说它只是单独的一个主句形式，因此谓语动词就是主句所要求的形式.
1.
表示对过去的虚拟:情态动词
would/could/should/ought
to
+
have
done
2.
表示对现在或将来的虚拟:情态动词
would/could/should/ought
to
+
do
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