如题所述
第1个回答 2010-04-15
学习" if " 引导的条件状语从句的用法,现在总结一下:
if 条件句不一般,几个要点记心间;
条件句,放在前,逗号要放句中间。
条件句表可能,主句多用将来时;
条件句表事实,主句常用现在时。
在 if 引导的条件状语从句中,如果从句谈论的是一个有可能发生的事实及其产生的相关的结果,主句用一般将来时态,从句用一般现在时态。如:
We can walk there if we can't find a bus .
If it rains tomorrow ,we will not go to the zoo.
What will you do if you find a panda in danger.
如果 if 条件句谈论的是重复发生和预示要发生的情景和事件,则主从句大多用一般现在时态。如:
If bears are in danger ,they attack people.
注意 :
在 if 引导的条件状语从句中,if 和条件句位置灵活,可直接放在主句后面,若 if 条件句放句首,
从句后面要加逗号,和主句隔开。
还要注意前后时态一致原则本回答被提问者采纳
if 条件句不一般,几个要点记心间;
条件句,放在前,逗号要放句中间。
条件句表可能,主句多用将来时;
条件句表事实,主句常用现在时。
在 if 引导的条件状语从句中,如果从句谈论的是一个有可能发生的事实及其产生的相关的结果,主句用一般将来时态,从句用一般现在时态。如:
We can walk there if we can't find a bus .
If it rains tomorrow ,we will not go to the zoo.
What will you do if you find a panda in danger.
如果 if 条件句谈论的是重复发生和预示要发生的情景和事件,则主从句大多用一般现在时态。如:
If bears are in danger ,they attack people.
注意 :
在 if 引导的条件状语从句中,if 和条件句位置灵活,可直接放在主句后面,若 if 条件句放句首,
从句后面要加逗号,和主句隔开。
还要注意前后时态一致原则本回答被提问者采纳
第2个回答 2010-04-17
1、主将从现 (主句为一般将来时,从句为一般现在时);
eg: If it rains(从句) , I will stay at home(主句).
=I will stay at home if it rains.
2、主句含有情态动词 (must、may、can etc.)从句为一般现在时;
eg: If you drive too fast , you may have an accident.
=You may have an accident if you drive too fast
3、主句为祈使句,从句要用一般现在时态;
eg: Don't play computer games if you don't finish your homework.
备注:
1、If 于句首时中间用逗号隔开,主句后不用逗号。
2、if 可用unless(除非...) 替换。 unless= if... not...
3、注意虚拟语气 主句和从句都为一般过去式
eg: If I was a bird , I could fly.(事实我不可能是鸟)
eg: If it rains(从句) , I will stay at home(主句).
=I will stay at home if it rains.
2、主句含有情态动词 (must、may、can etc.)从句为一般现在时;
eg: If you drive too fast , you may have an accident.
=You may have an accident if you drive too fast
3、主句为祈使句,从句要用一般现在时态;
eg: Don't play computer games if you don't finish your homework.
备注:
1、If 于句首时中间用逗号隔开,主句后不用逗号。
2、if 可用unless(除非...) 替换。 unless= if... not...
3、注意虚拟语气 主句和从句都为一般过去式
eg: If I was a bird , I could fly.(事实我不可能是鸟)
第3个回答 2019-05-17
一.宾语从句的定义
置于动词、介词等词性后面起宾语作用的从句叫宾语从句。宾语从句的语序必须是陈述语序。谓语动词、介词、动词不定式,v.-ing形式后面都能带宾语从句。有些形容词(afraid,sure,glad等)之后也可以带宾语从句。
二.宾语从句中引导词的用法在复合句中作主句的宾语,引导词有:
连词:that
(that
常可省略),whether,
if
代词:who,
whose,
what
,which
副词:when
,where,
how,
why
等。
(一)that引导的宾语从句(在非正式场合that可以省略)
可跟that从句做宾语的动词有:
say,
think,
insist,
wish,
hope,
demand,
imagine,
wonder,
know,
suppose,
see,
believe,
agree,
admit,
deny,
expect,
explain,
order,
command,
feel,
dream,
suggest,
hear,
mean,
notice,
prefer,
request,
require,
propose,
declare,
report等。
例句:The
boy
believes
that
he
will
travel
through
space
to
other
planets.
注意事项:当主句谓语动词是
think,
believe,
suppose,
expect
等词,而宾语从句的意思是否定时,常把否定转移至主句表示。
例句:I
don’t
think
it
is
right
for
him
to
treat
you
like
that.
在以下情况中that不能省略
当句中的动词后接多于两个由that引导的宾语从句时,第一个that可省,但后面的that不可省。例句:He
said
(that)
you
were
too
young
to
understand
the
matter
and
that
he
was
asked
not
to
tell
you.
当主句的谓语动词与that宾语从句之间有插入语时,that一般不可省。例句:Just
then
I
noticed,
for
the
first
time,
that
our
master
was
wearing
his
fine
green
coat
and
his
black
silk
cap.
当that从句是双宾语中的直接宾语时,that不可省。例句:I
can’t
tell
him
that
his
mother
died.
注意事项:许多带复合宾语的句子,that引导的宾语从句经常移到句子后部,而用it作形式宾语。
例句:I
find
it
necessary
that
we
should
do
the
homework
on
time.
(二)由whether,if
引导的宾语从句
由whether(if)引导的宾语从句,实际上是一般疑问句演变而来的。意思是“是否”。宾语从句要用陈述句语序。一般说来,在宾语从句中whether与if可以互换使用,但在特殊情况下if与whether是不能互换的。
例句:I
wonder
whether(if)
they
will
come
to
our
party.
只能用whether,不能用if引导的宾语从句
在带to的不定式前例句:We
decided
whether
to
walk
there.
在介词的后面例句:I’m
thinking
of
whether
we
should
go
to
see
the
film.
在动词后面的宾语从句时例句:We
discussed
whether
we
had
a
sports
meeting
next
week
直接与or
not连用时例句:I
can’t
say
whether
or
not
thet
can
come
on
time.
只能用if不能用whether引导的宾语从句
if引导条件状语从句,意为“如果”例句:The
students
will
go
on
a
picnic
if
it
is
sunny.
if引导否定概念的宾语从句时例句:He
asked
if
I
didn’t
come
to
school
yesterday.
引导状语从句even
if(即使)和as
if(好象)时例句:He
talks
as
if
he
has
known
all
about
it.
(三)连接代词和连接副词引导的宾语从句
这样的宾语从句实际上是由特殊疑问句变化而来的,宾语从句要用陈述句语序。用于这种结构的动词常常是:see,
say,
tell,
ask,
answer,
know,
decide,
show,
find
out,
imagine,
suggest,
doubt,
wonder,
discover,
understand,
inform,
advise等。
英语中的连接代词有:who,whom,whose,which,what,在句中担任主语、宾语、定语或者表语。
例句:Can
you
tell
me
whom
you
are
waiting
for?
英语中的连接副词有:when,where,why,how,在句中担任状语的成分。
例句:None
of
us
knows
where
these
new
parts
can
be
bought.
三.宾语从句的语序
宾语从句的语序是陈述句语序即:连接代词/副词+主语+谓语+其他成分。例句如下:
I
don’t
know
what
they
are
looking
for.
Could
you
tell
me
when
the
train
will
leave?
Can
you
imagine
what
kind
of
man
he
is?
四.宾语从句的时态
主句是一般现在时,从句根据实际情况使用任何时态。例句:The
headmaster
hopes
everything
goes
well.
主句是过去时态,从句须用过去时态的某种形式。例句:She
was
sorry
that
she
hadn’t
finished
her
work
on
time.
当宾语从句表示的是一个客观真理或者事实时,即使主句是过去时,从句也用一般现在时态。例句:The
teacher
told
his
class
that
light
travels
faster
than
sound.
置于动词、介词等词性后面起宾语作用的从句叫宾语从句。宾语从句的语序必须是陈述语序。谓语动词、介词、动词不定式,v.-ing形式后面都能带宾语从句。有些形容词(afraid,sure,glad等)之后也可以带宾语从句。
二.宾语从句中引导词的用法在复合句中作主句的宾语,引导词有:
连词:that
(that
常可省略),whether,
if
代词:who,
whose,
what
,which
副词:when
,where,
how,
why
等。
(一)that引导的宾语从句(在非正式场合that可以省略)
可跟that从句做宾语的动词有:
say,
think,
insist,
wish,
hope,
demand,
imagine,
wonder,
know,
suppose,
see,
believe,
agree,
admit,
deny,
expect,
explain,
order,
command,
feel,
dream,
suggest,
hear,
mean,
notice,
prefer,
request,
require,
propose,
declare,
report等。
例句:The
boy
believes
that
he
will
travel
through
space
to
other
planets.
注意事项:当主句谓语动词是
think,
believe,
suppose,
expect
等词,而宾语从句的意思是否定时,常把否定转移至主句表示。
例句:I
don’t
think
it
is
right
for
him
to
treat
you
like
that.
在以下情况中that不能省略
当句中的动词后接多于两个由that引导的宾语从句时,第一个that可省,但后面的that不可省。例句:He
said
(that)
you
were
too
young
to
understand
the
matter
and
that
he
was
asked
not
to
tell
you.
当主句的谓语动词与that宾语从句之间有插入语时,that一般不可省。例句:Just
then
I
noticed,
for
the
first
time,
that
our
master
was
wearing
his
fine
green
coat
and
his
black
silk
cap.
当that从句是双宾语中的直接宾语时,that不可省。例句:I
can’t
tell
him
that
his
mother
died.
注意事项:许多带复合宾语的句子,that引导的宾语从句经常移到句子后部,而用it作形式宾语。
例句:I
find
it
necessary
that
we
should
do
the
homework
on
time.
(二)由whether,if
引导的宾语从句
由whether(if)引导的宾语从句,实际上是一般疑问句演变而来的。意思是“是否”。宾语从句要用陈述句语序。一般说来,在宾语从句中whether与if可以互换使用,但在特殊情况下if与whether是不能互换的。
例句:I
wonder
whether(if)
they
will
come
to
our
party.
只能用whether,不能用if引导的宾语从句
在带to的不定式前例句:We
decided
whether
to
walk
there.
在介词的后面例句:I’m
thinking
of
whether
we
should
go
to
see
the
film.
在动词后面的宾语从句时例句:We
discussed
whether
we
had
a
sports
meeting
next
week
直接与or
not连用时例句:I
can’t
say
whether
or
not
thet
can
come
on
time.
只能用if不能用whether引导的宾语从句
if引导条件状语从句,意为“如果”例句:The
students
will
go
on
a
picnic
if
it
is
sunny.
if引导否定概念的宾语从句时例句:He
asked
if
I
didn’t
come
to
school
yesterday.
引导状语从句even
if(即使)和as
if(好象)时例句:He
talks
as
if
he
has
known
all
about
it.
(三)连接代词和连接副词引导的宾语从句
这样的宾语从句实际上是由特殊疑问句变化而来的,宾语从句要用陈述句语序。用于这种结构的动词常常是:see,
say,
tell,
ask,
answer,
know,
decide,
show,
find
out,
imagine,
suggest,
doubt,
wonder,
discover,
understand,
inform,
advise等。
英语中的连接代词有:who,whom,whose,which,what,在句中担任主语、宾语、定语或者表语。
例句:Can
you
tell
me
whom
you
are
waiting
for?
英语中的连接副词有:when,where,why,how,在句中担任状语的成分。
例句:None
of
us
knows
where
these
new
parts
can
be
bought.
三.宾语从句的语序
宾语从句的语序是陈述句语序即:连接代词/副词+主语+谓语+其他成分。例句如下:
I
don’t
know
what
they
are
looking
for.
Could
you
tell
me
when
the
train
will
leave?
Can
you
imagine
what
kind
of
man
he
is?
四.宾语从句的时态
主句是一般现在时,从句根据实际情况使用任何时态。例句:The
headmaster
hopes
everything
goes
well.
主句是过去时态,从句须用过去时态的某种形式。例句:She
was
sorry
that
she
hadn’t
finished
her
work
on
time.
当宾语从句表示的是一个客观真理或者事实时,即使主句是过去时,从句也用一般现在时态。例句:The
teacher
told
his
class
that
light
travels
faster
than
sound.
第4个回答 2019-02-14
"if"从句必须满足“主将从现”,而“主将从现”分为三钟情况,(1)主句满足一般将来时态(2)主句中含有情态动词(3)主句是一个祈使句。出现这三种情况,"if”从句必须用一般现在时态。