如题所述
经典例句]
1.
If
you
copy
my
homework
this
time,
you
will
start
a
bad
habit.
2.
I’ll
ask
the
teacher
for
help
if
I
don’t
understand.
3.
If
the
traffic
lights
are
red,
you
must
stop
and
wait.
4.
You
can
pass
the
exam
if
you
work
hard
=
Work
hard,
and
you
will
pass
the
exam.
5.
If
you
don’t
hurry
up,
you
will
be
late
again.
=
Hurry
up,
or
you
will
be
late
again.
[要点演绎]
◆结构:if是从属连词,意为“如果”,用来引导条件状语从句。if引导的条件状语从句既可放在主句之前,也可放在主句之后。从句位于主句之前时,常用逗号将其与主句隔开。如句1、3、5。
◆时态:主句用一般将来时
(如句1、2)或主句谓语中含情态动词
(如must,
can,
could,
should等,如句3、4)
时,
if引导的条件状语从句用一般现在时表示将来意义。
◆变换:含有if引导的条件状语从句的复合句中,当主句主语和从句主语均为you时,可转换为“祈使句,and
+
简单句
(如句4)”或“祈使句,or
+
简单句
(如句5)”。
1.
If
you
copy
my
homework
this
time,
you
will
start
a
bad
habit.
2.
I’ll
ask
the
teacher
for
help
if
I
don’t
understand.
3.
If
the
traffic
lights
are
red,
you
must
stop
and
wait.
4.
You
can
pass
the
exam
if
you
work
hard
=
Work
hard,
and
you
will
pass
the
exam.
5.
If
you
don’t
hurry
up,
you
will
be
late
again.
=
Hurry
up,
or
you
will
be
late
again.
[要点演绎]
◆结构:if是从属连词,意为“如果”,用来引导条件状语从句。if引导的条件状语从句既可放在主句之前,也可放在主句之后。从句位于主句之前时,常用逗号将其与主句隔开。如句1、3、5。
◆时态:主句用一般将来时
(如句1、2)或主句谓语中含情态动词
(如must,
can,
could,
should等,如句3、4)
时,
if引导的条件状语从句用一般现在时表示将来意义。
◆变换:含有if引导的条件状语从句的复合句中,当主句主语和从句主语均为you时,可转换为“祈使句,and
+
简单句
(如句4)”或“祈使句,or
+
简单句
(如句5)”。
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