Unit 7 Nobody wins (Ⅱ)语法之if和unless 引导的条件状语从句学案（部分答案）2021-2022学年牛津上海版英语八年级上册

if引导的条件状语从句与if引导的宾语从句之间的区别用法要特别注意。if
引导条件状语从句，表示“如果”，从句需要遵循主将从现的原则；if
引导宾语从句，表示“是否”，从句不必遵循主将从现的原则，这是一个易错点，需要细心区别。
一.
if
引导的条件状语从句之基本用法
1.
定义
If
意为“如果”，引导条件状语从句，表示假如从句的动作发生，主句的动作就(不)会发生。
If
it
doesn't
rain,
I
will
go
to
the
cinema
tomorrow.
2.
位置
从句位置灵活，可放在主句之前，但要用逗号与主句隔开；也可放在主句之后。
My
mother
will
take
me
to
the
park
if
she
is
free.
If
my
mother
is
free,
she
will
take
me
to
the
park.
3.
时态
若主句为下列情形之一，条件状语从句要用一般现在时
(1)
当主句为一般将来时：
(2)
当主句的谓语中含有can,
may,
must
等情态动词时：
(3)
当主句为祈使句时：
If
he
comes,
he
will
bring
his
violin.
If
you
lose
weight,
you
must
eat
less
meat.
If
you
are
not
strong
enough,
please
don't
take
part
in
such
an
activity.
注：助记口诀
if
条件句不一般，三个要点记心间：
主将从现、主情从现、主祈从现。
注意：如果
if
条件句讲述自然规律，肯定会发生的事情或客观事实，主句和if从句都用一般现在时态。（主现从现）
If
you
take
a
fish
out
of
water,
it
dies.
如果把鱼从水中拿出，它会死。
【即学即练】
1.
______
you
study
hard,
you
will
get
good
grades.
A.
If
B.
So
C.
And
D.
But
【参考答案】A，if
引导的状语从句遵循“主将从现”的原则，又根据句意“如果你好好学习，你会取得好成绩。”故选A。
2.
If
Mary
_______
free
tomorrow,
I
will
ask
Tom
instead.
A.
doesn’t
B.
won’t
C.
is
D.
isn’t
【参考答案】D，if
引导的状语从句遵循“主将从现”的原则，又根据句意“如果Mary
明天没有时间，我会请Tom
代替她”，故选C。
3.
If
it
rains
this
weekend,
we
________
for
a
picnic.
A.
won’t
go
B.
will
go
C.
goes
D.
go
【参考答案】A，if
引导的状语从句遵循“主将从现”的原则，又根据句意“如果这周末下雨，我们就不去野餐了”，故选A。
4.
If
she
_______
here
tomorrow,
I
_______
to
the
park
with
her.
A.
comes;
will
go
B.
will
come;
will
go
C.
comes;
go
D.
will
come;
go
【参考答案】A，if
引导的状语从句遵循“主将从现”的原则，又根据句意“如果她明天来，我就陪她去野餐”，故选A。
二.
If
引导的条件状语从句之句型转换
1.
借助“祈使句+and/or+句
子”来转换(and
表顺承，or
表转折)
If
you
study
hard,
you
will
pass
the
exam
easily.
=
Study
hard,
and
you
will
pass
the
exam
easily.
=
Study
hard,
or
you
won’t
pass
the
exam.
2.
借助without
或with
来转换
If
there
is
no
water,
fish
will
die.
=
Fish
will
die
without
water.
【即学即练】
1.
Take
the
exam
with
great
care,
______
you
won’t
get
a
good
mark.
A.
if
B.
unless
C.
or
D.
and
【参考答案】C，根据句意“考试时一定要认真，否则你不会取得好成绩”可知表示“转折”，故选C，本句可以转换为“If
you
take
the
exam
with
great
care,
you
will
get
a
good
mark.”。
2.
Work
harder
______you
will
find
it
not
difficult
to
learn.
A.
if
B.
unless
C.
or
D.
and
【参考答案】D，根据句意“再努力一点，你会发现这个学起来并不难”可知表示“顺承”，故选D，本句可以转换为“If
you
work
harder,
you
will
find
it
not
difficult
to
learn.”。
3.
Hurry
up,
or
you
will
be
late.
(改为if引导的条件状语从句)
__________________________________________________________________5
【参考答案】If
you
don’t
hurry
up,
you
will
be
late.
4.
If
you
help
me,
I’ll
finish
the
work
soon.
(改为with结构)
__________________________________________________________________
【参考答案】With
your
help,
I’ll
finish
the
work
soon.
四.
If…not/
unless用法
1.
unless也可引导条件状语从句，相当于?if…not…,
意思是“如果不；除非…否则…”。
Unless
you
go
at
once,
you
will
be
late.
=If
you
do
not
go
at
once,
you
will
be
late.
如果不马上走，你就会迟到。
2.位置：从句位置灵活，可放在主句之前，但要用逗号与主句隔开；也可放在主句之后。
Unless
you
go
at
once,
you
will
be
late.
She?will?keep?on?singing?unless?she?is?told?to?stop.?
3.
时态：主将从现、主情从现、主祈从现。
4.
句型转换
可以用or(否则)?来做同义句转换
Unless?you?listen?carefully,?you?won’t?know?the?answer.
=?If?you?don’t?listen?carefully,?you?won’t?know?the?answer.
=?You?should?listen?carefully,?or?you?won’t?know?the?answer.
【即学即练】
1.
Take
the
exam
with
great
care,
______
you
won’t
get
a
good
mark.
A.
if
B.
unless
C.
or
D.
and
【参考答案】C，根据句意“考试细心点，否则你将不会取得好成绩。”故选C。
2.
I
won't
lend
you
my
car
_________
you
promise
to
return
it
before
12:00.
A.
if
B.
unless
C.
so
D.
but
【参考答案】B，unless引导的状语从句遵循“主祈从现”的原则，又根据句意“除非你承诺12点之前还，否则我不会把我的车借给你。”故选B。
3.
You
can’t
catch
the
bus
_________
you
get
up
early.
A.
if
B.
or
C.
unless
D.
but
【参考答案】C，unless引导的状语从句遵循“主情从现”的原则，又根据句意“除非你早点起床，否则你赶不上车。”故选C。
4.
You
_________
something
easily
unless
you
_________
it.
A.
forget;
understand
B.
forget;
will
understand
C.
will
forget;
understand
D.
forgets;
understands
【参考答案】C，unless引导的状语从句遵循“主将从现”的原则，又根据句意“除非你理解它，否则你就很容易忘记。”故选C。
一．时间状语从句
1.
概念
时间状语从句就是在复合句中表示主句动作发生时间的状语从句。常用的连接词有:
when,
while,
after,
before,
since,
ever
since,
as
soon
as,
once,
till,
until.
A.
when,
while引导时间状语从句
(1)
when的用法
when既可指时间点，也可指时间段（即：从句动词可以是短暂的也可是延续的）；主从句动作可同时也可先后发生。
I
was
thin
when
I
was
a
child.
当我是个孩子的时候,我很瘦。
It
was
raining
when
I
arrived.我到达时，天正在下雨。
(2）while用法
while只能指一段时间，从句中的动词必须是延续性动词。强调某一段时间内发生主句动作，相当于during
the
time
that....
My
mother
was
cooking
while
I
was
doing
my
homework.
当我在做作业时，妈妈在做饭。
I
am
safe
while
I
am
here.我在这儿的时候，我很安全。
注意
while除引导时间状语从句外，还引导对比句，作“然而”讲；并可在句首引出让步状语从句作“虽然···但”讲。
I
like
watching
TV,
while
he
likes
reading.
我喜欢看电视，而他喜欢读书。
While
he
has
his
own
car,
he
often
uses
mine.
尽管他自己有车，他却常用我的。
【即学即练】用when,while填空
_________Margo
was
talking
on
the
phone,
her
sister
walked
in.
_________we
visited
the
school,
the
children
were
playing
games.
_________Sarah
was
at
home,
I
was
going
to
class.
解析：1.while
2.when
3.while
before和after引导的时间状语从句
(1)
before引导的从句不再用否定式的谓语，并且当before引导的从句位于主句之后，有时译成“就，才”。还要注意主句和从句之间的时间关系。当主句用将来时，从句总是用现在时；如果before引导的从句谓语用的是过去时，则主句动词多用过去完成时，这样以便体现动作发生的先后。如：
It
will
be
four
days
before
they
come
back.
（主将从现，一一对应）
他们要过四天才能回来。
Einstein
almost
knocked
me
down
before
he
saw
me.
（几乎同时发生）
爱因斯坦几乎把我撞倒才看到我。
My
father
had
left
for
Canada
just
before
the
letter
arrived.
（主过完从过）
我父亲恰好在信到之前去加拿大了。
They
had?not?been
married
four
months
before
they
were
divorced.
他们结婚还不到四个月就离婚了。
(2)after表示主句动作发生在从句动作之后。主句和从句的动作的时间关系正好与before引导的从句相反。如：
After
you
think
it
over,
please
let
me
know
what
you
decide.
你仔细考虑过以后，告诉我你是怎样决定的。
After
we
had
finished
the
work,
we
went
home.
完成工作之后，我们回家了。（从句用过去完成时，主句用一般过去时）
C.
表示一…….就的句型
(1)
as
soon
as/once
As
soon
as
he
arrives,
I'll
call
you.他一到，我就给你打电话。（as
soon
as
侧重时间或动作先后衔接紧，而once侧重条件，表示“一旦...”）
(2)
on
doing
sth/on
one's
+
n.作时间状语
On
arriving
at
the
station,
the
thief
was
arrested.
一到达车站，这个小偷就被逮捕了。
On
his
arrival
in
Paris,
he
was
recognized
as
a
noble
and
thrown
into
prison.
他一到达巴黎，就被认出是一个贵族，并被投入监狱。
D.
until和till
(1)“延续性动词肯定式+until”表示“动作延续到…为止，”译为“直到…为止”，如：
I
waited
for
him
until
he
came
back.
我一直等到他回来。
(2)“终止性动词的否定式+
until”表示“直到···才”。
He
didn't
go
to
bed
until
he
had
finished
his
work.
直到完成工作他才睡觉。
(3)用于强调句式“It
is
not
until
...that
...”
It
was
not
until
the
professor
came
that
we
began
the
experiment.
在教授到来之后，我们才开始实验。
(4)
not
until放在句首时，主句倒装。
Not
until
he
graduated
did
he
succeed
in
obtaining
this
compound.
直到他毕业他才成功获得这种化合物。
【即学即练】
单项选择
1.
It
was
quiet
________
those
big
trucks
started
coming
through
the
town.
A.
before
B.
after
C.
until
D.
unless?
2.
It
seemed
only
seconds
________
the
boy
finished
washing
his
face.
A.
when
B.
before
C.
after
D.
even
if
3.
Hardly
had
he
reached
the
school
gate
________
the
bell
rang.
A.
while
B.
when
C.
as
D.
as
soon
as?
4.We
were
told
that
we
should
follow
the
main
road
_____
we
reached
the
central
railway
station.
A.
whenever???
B.
until??
C.
while???
D.
wherever
5.
I
recognized
you
________
I
saw
you
at
the
airport.
A.
the
moment
B.
while
C.
after
D.
once?
6.
He
was
about
to
go
to
bed
________
the
doorbell
rang.
A.
while
B.
as
C.
before
D.
when
7.________I
listen
to
your
advice,
I
get
into
trouble.
A.
Every
time
B.
When
C.
While
D.
Until
8.
_____
John
was
watching
TV,
his
wife
was
cooking.
A.
As
soon
as
B.
As
C.
While
D.
Till
9.
The
children
ran
away
from
the
orchard(果园)
______
they
saw
the
guard.
A.
the
moment
B.
after
C.
before
D.
as
10.
No
sooner
had
I
arrived
home
_____
it
began
to
rain.
A.
when
B.
while
C.
as
D.
than
解析：1-5
CBBBA?
DACAD?
一、句型转换
1.
If
you
work
harder,
you’ll
pass
the
exam.
Work
harder,
______
you’ll
pass
the
exam.
2.
Put
on
your
coat,
or
you’ll
catch
a
cold.
7
______you
______
put
on
your
coat,
you’ll
catch
a
cold.
3.
If
you
don’t
help
me,
I
can’t
finish
my
work
on
time.
______
your
help,
I
can’t
finish
my
work
on
time.
4.
If
you
play
basketball
here,
you
may
break
the
windows.
______play
basketball
here,
______
you
may
break
the
windows.
5.
If
you
don’t
hurry
up,
you’ll
miss
the
train.
Hurry
up,
______
you’ll
miss
the
train.
6.
Hurry
up,
or
you
will
be
late.
(改为if
引导的条件状语从句)
__________________________________________________________________
7.
If
you
help
me,
I’ll
finish
the
work
soon.
(改为with
结构)
__________________________________________________________________
二、根据句意，用if或unless连接句子
1.
They
won’t
understand
you.
You
speak
too
fast.
__________________________________________________________________
2.
She
won’t
play
the
piano
well.
She
keeps
on
practising
it
every
day.
__________________________________________________________________
3.
I’m
free
this
weekend.
I’ll
go
to
the
library.
__________________________________________________________________
4.
A
dog
barks.
It
is
angry.
__________________________________________________________________
5.
You
take
a
fish
out
of
water.
It
dies.
__________________________________________________________________
三、用方框中的单词填空。
when
、before、
after
、as
、since、
while、
until
、as
soon
as
1．Mum
was
making
cookies
in
the
kitchen
______the
telephone
rang.
2．I
was
watching
TV
______
my
wife
was
cooking.
3．He
had
worked
in
a
factory
for
two
years
______
he
went
to
college.
4．I
shall
play
chess
with
you
______
I
finish
watching
TV.
5．He
didn’t
get
to
the
airport
______
it
was
dark.
6．She
sang
______
she
went
along.
7．I
haven’t
heard
from
him
_____
he
went
to
America.
8．We
found
the
books
two
days
____
he
had
gone
away.
四、单项选择
1._______
you
put
your
heart
into
studies,
you
can’t
get
good
grades
in
the
exam.
A.
If
B.
Unless
C.
When
D.
Though
2.
If
he
____
harder,
he
will
catch
up
with
us
soon.
A.
study
B.
studies
C.
will
study
D.
studied
3.
—I
wonder
if
Yao
Ming
______
to
our
school
this
weekend.
—If
he
_______,
we
will
be
very
happy.
A.
comes;
comes
B.
comes;
will
come
C.
will
come;
comes
D.
will
come;
will
come
4.
We
didn’t
start
the
party
___
everybody
arrived.
A.
since
B.
if
C.
until
5.
____
they
are
brothers,
they
don’t
look
the
same.
A.
Though
B.
If
C.
so
D.
Who
6.
If
it
_______
tomorrow,
I’ll
stay
at
home.
A.
will
rain
B.
rains
C.
rained
7.
I
don’t
know
when
he
______
tomorrow.
If
he
______,
I’ll
let
you
know.
A.
comes;
comes
B.
comes;
will
come
C.
will
come;
comes
D.
will
come;
will
come
8.
—Would
you
mind
______
I
ask
you
a
question?
—Of
course
not,
please
do.
A.
that
B.
if
C.
which
D.
when
9.
Do
you
know
the
saying
“If
you
______
life,
life
_____
you
back.”?
A.
love;
love
B.
love;
will
love
C.
will
love;
love
D.
will
love;
will
love
10.
Study
hard,
_____
you
can
pass
the
exam
easily.
A.
if
B.
and
C.
or
D.
unless
11.
The
meeting
didn't
start___
everyone
was
there.
A.
Because
B.
until
C.
why
D.
if
12.
The
boy
___
to
bed
___
his
mother
came
in.
went
not;
until
B.
didn't
go;
after
C.
went;
until
D.
didn't
go;
until
13.
He
_________
wait
until
the
rain
_________
.
A．won’t,
will
stop　　　
B．won’t,
stop
C．will,
stops　　　
D．will,
will
stop
14.
As
soon
as
Jane
_________
here,
I’ll
post
the
letter
to
Mike.
A．leave　
B．will
leave
C．leaves
D．left
15.
It
was
already
five
o’clock
_________
we
got
home.
A．when　
B．while
C．because　　
D．if
16.
—I’m
going
to
the
post
office.
—________
you’re
there,
can
you
get
me
some
stamps?
A．As　　　
B．While
C．Because　　
D．If
17.
Joan
and
Mary
haven’t
seen
each
other_____they
left
school
five
years
ago.
A．as　　
B．before
C．after　　
D．since
18.
I
will
let
you
know
about
it
as
soon
as
I
_________
the
news.
A．will
get　
B．gets
C．got　　
D．get
19.
He
___
back
until
the
work
___
done.
A.
isn't;
will
be
B.
isn't;
is
C.
won't
be;
will
be
D.
won't
be;
is
20.
I
call
the
police
for
help_________
I
saw
the
thief.
A．while
　
B．before
C．as
soon
as
D．after
if
引导的条件状语从句
1.基本用法
若主句为下列情形之一，条件状语从句要用一般现在时：
1.
当主句为一般将来时；
2.
当主句的谓语中含有can,
may,
must
等情态动词时；
3.
当主句为祈使句时。
2.句型转换
1.
借助“祈使句+and/or+句子”来转换(and
表顺承，or
表转折)
2.
借助without
或with
来转换
4.If…not/
unless用法
unless也可引导条件状语从句，相当于
if…not…,
意思是“如果不；除非…否则…”。
时间状语从句
1.
概念
2.
while,
when引导的状语从句
3.
before,
after引导的状语从句
4.
表示一...就的句型as
soon
as
5.
until和till的区别
学生易错点整理：
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