what
引导名词从句（包括
主语从句、宾语从句、表语从句、
同位语从句)，它在从句中可以作主语、宾语、表语、、定语、宾补。如：
what
he
said
is
right.
他说得对。
she
is
no
longer
what
she
used
to
be.
她不是过去的她了。
they
don't
know
what
happened.他们不知道发生了什么。
are
you
sure
what
books
he
likes
reading?
你知道他喜欢读什么书吗？
he
knows
what
people
call
him.
他知道人们叫他什么。
the
question
what
makes
the
matter
worse
has
been
puzzling
me.
是什么使情况更糟了这个问题一直在困惑着我。