Question

主语从句中的what是指什么?

Answer 1

He
is
what
is
known
as
a
“bellyacher”这不是主语从句，而是表语从句，意思是“他是所谓的抱怨家”。what是缩合连接代词。
用作表语的从句叫做表语从句(predicative
clause)。引导表语从句的关联词有疑问代词、疑问副词、缩合连接代词、从属连接词等。如：
The
problem
is
whom
we
can
get
to
replace
her.
问题是我们能找到谁去替换她呢。(关联词是疑问代词whom)
The
question
is
how
he
did
it.
问题是他是如何做此事的。(关联词是疑问副词how)
That
was
what
she
did
this
morning
on
reaching
the
attic.
那就是她今晨上了阁楼干的。(关联词是缩合连接代词what)
He
looked
just
as
he
had
looked
ten
years
before.
他看起来还与十年前一样。(关联词是从属连词as)
从属连接词that有时亦可引导表语从句，如：
The
trouble
is
that
I
have
lost
his
address.
麻烦是我把他的地址丢了。
口语中，可以省略从属连接词that，在省略处加一个逗号。
The
trouble
is,
I
have
lost
his
address.
麻烦是我把他的地址丢了。
从属连接词whether有时亦可引导表语从句，如：
The
question
is
whether
they
will
be
able
to
help
us.
问题是他们是否能帮我们。
从属连接词if一般不用来引导表语从句，但as
if却可引导表语从句，表语从句里的动词常常用虚拟语气来表示，如：
All
this
was
over
twenty
years
ago,
but
it’s
as
if
it
were
only
yesterday.(这都是20多年前的事了，但宛如昨天一样。)