it is said that为什么不是宾语从句
是主语从句
参考：
主语从句
定义:在句子中担当主语的是一个从句,这个从句就叫做主语从句。
主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
1、主语从句常用it作形式主语，一般常用句型为：
It
is+{名词/形容词/过去分词}+主语从句例如：
It
is
still
a
question
whether
she
will
come
or
not.
It
is
strange
that
you
should
like
him.
It
is
still
unknown
which
team
will
win
the
match.
另外，还有一些比较多见的结构：
It
turned
out
that……；
It
has
been
proved
that……;
It
happened/occurred
that……；
It
is
well-known
that……等等
2.
用it
作形式主语的结构
(1)
It
is
+名词+that从句
It
is
a
fact
that
…
事实是…
It
is
an
honor
that
…非常荣幸
It
is
common
knowledge
that
…是常识
(2)
it
is
+形容词+that从句
It
is
natural
that…
很自然…
It
is
strange
that…
奇怪的是…
(3)
it
+不及物动词+that从句
It
seems
that…
似乎…
It
happened
that…
碰巧…
(4)
it
is+过去分词+that从句
It
is
reported
that…
据报道…
It
has
been
proved
that…
已证实…
主语从句不可位于句首的五种情况
(1)
if
引导的主语从句不可居于复合句句首.
(2)
It
is
said
,(reported)
…结构中的主语从句不可提前.
例如： It
is
said
that
President
Jingo
will
visit
our
school
next
week.
(3)
It
happens…,It
occurs…
结构中的主语从句不可提前.
例如： It
occurred
to
him
that
he
failed
in
the
examination.
(4)
It
doesn’t
matter
how/whether
…结构中的主语从句不可提前.
例如： It
doesn’t
matter
whether
he
is
wrong
or
not.
(5)
含主语从句的复合句是疑问句时,主语从句不可提前.
例如： Is
it
likely
that
it
will
rain
in
the
evening?
你的提问是其中(2)
It
is
said
,(reported)
…结构中的主语从句不可提前.
例如： It
is
said
that
President
Jingo
will
visit
our
school
next
week.