1.that引导宾语从句无意义，不充当句子成分常省略。但下列情况除外：
（1）介词宾语从句的that不省略
（2）
and连接的几个从句，第二个从句以后的从句的that不省略。
he
told
me
that
he
had
two
sons
and
that
they
both
had
gone
to
college.
（3）在动词+it+宾语补足语+宾语从句结构中，that不省略。
i
heard
it
said
that
he
had
gone
abroad
we
found
it
impossible
that
he
could
finish
it
in
such
a
short
time
2.whether
,if
引导宾语从句：两词可互换，但是下列情形除外：
（1）whether从句中有or
not
（2）whether从句做介词宾语
everything
depends
on
whether
you
agree
with
us
3.许多带复合宾语的句子，宾语从句经常移到句子后部，而用it做形式宾语。结构常是：
主语+动词+it+形容词/名词等宾语补足语+宾语从句
we
think
it
wrong
that
he
told
a
lie
to
everyone
4.宾语从句的语序要用陈述句语序
false:
he
is
wondering
when
can
he
finish
this
difficult
job.
right:
he
is
wondering
when
he
can
finish
this
difficult
job.
b
有时候可以用it
作形式宾语，而把真正的宾语从句放在后面。
bad:
i
thought
that
he
could
finish
this
job
in
just
two
hours
impossible.
good:
i
thought
it
impossible
that
he
could
finish
this
job
in
just
two
hours.
bad:
he
left
whether
we
should
continue
this
project
to
my
judgment.
good:
he
left
it
to
my
judgment
whether
we
should
continue
this
project.
c
带有宾语从句的复合句的否定形式一般是否定主句。
bad:
i
think
he
doesn’t
like
the
english
teacher.
good:
i
don’t
think
he
likes
the
english
teacher.
d
主句一般过去时态，从句也要用过去时态；具体细节请看第一部分。
false:
he
wanted
to
know
why
he
is
crying
in
the
corner.
right:
he
wanted
to
know
why
he
was
crying
in
the
corner.
bu
哪些宾语从句不可以省略引导词that
1当that做learn,suggest,explain,agree,wonder,prove,mean,state,feel,hold等动词的宾语时;
2当宾语从句较长时;
3当主语状语置于主句尾,宾语从句之前时;
4当主语谓语动词(包括非谓语动词)与宾语从句之间有插入语时;
5当一个动词带有两个或两个以上宾语从句时,此时第一个that可以省略,第二个that不可以省略;
6当宾语从句中的主语是this,that或this,that做主语的定语时;
7当宾语从句是双宾语中的直接宾语时;
8当宾语从句的主语是非谓语动词或主语从句时;
9当主语中的谓语动词是固定词组时;
10当宾语从句有it做其先行词时;
11在直接引语中,转述分句把宾语从句隔开时.
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