Question

如何区分名词性从句?

Answer 1

名词性从句是在句子中起名词作用的主谓结构，它可以在主从复合句中作主语、宾语、
表语、介词的宾语以及同位语。
1.
主语从句
主语从句可以由连词that,
wh-疑问词或名词性关系词引导。
⑴由连词that引导：从句可以位于句首，但常常用形式主语it替代，从句本身则放在
主句后面，如：
That
he
will
come
to
the
party
is
certain.
It
happened
that
the
harvest
was
bad
that
year.
Is
it
true
that
she
has
never
been
there?
通常在口语或非正式文体中，that常可省略，但必须是在用先行词it的情况下，如：
It’s
a
pity
(that)
you
are
leaving.
⑵由wh-疑问词引导：从句既可以前置，又可以借助于先行词it后置。如：
Who
cleaned
the
meeting
room
is
unknown.
It’s
still
a
question
when
we
shall
have
our
sports
meet.
It
is
uncertain
whether
he
will
come.
注意：在疑问句中，wh-疑问词所引导的从句不能位于句首，如：
Is
it
known
where
she
went?
⑶主语从句也可由名词性关系词引导，这类从句只能位于句首，如：
Where
she
went
was
Los
Angeles.
What
will
be,
will
be.
Whomever
you
invite
will
be
welcome.
2.
宾语从句
⑴宾语从句可用that引导，这时that仅起连接作用，不充当从句中的成分。如果连接词
要在从句中起语法作用，就要使用连接词what等来引导从句。
I
believe
that
he
is
honest.
We
fully
understood
what
he
meant.
⑵有些形容词的后面也可跟宾语从句。这类形容词有：certain,
afraid,
aware,
sorry,
sure,
worried等。如：
I’m
afraid
that
you
are
wrong
on
this
point.
I
am
aware
that
you
have
been
exceptionally
kind
to
me.
⑶宾语从句也可以用how,
when,
who,
which,
where,
why等词引出，此时即使主句是一
个疑问句，宾语从句也必须保持陈述句的语序。如：
Go
and
ask
why
he
was
late
yesterday.
Can
you
tell
me
where
the
hospital
is?
⑷跟在介词后面的宾语从句一般不能由that来引出，只限于except,
in,
but,
besides,
save
等五个介词的宾语从句，其它介词后面不能跟由that引出的宾语从句，而只能跟由what,
how,
whether等引出的宾语从句。
You
are
wrong
in
that
you
took
effect
for
cause.
I
would
go
with
you,
except
that
I
have
to
work
that
day.
They
were
arguing
about
what
was
to
be
done.
I’m
thinking
of
whom
I
should
ask
for
help.
3.
表语从句
表语从句通常由that引出，当然how,
why,
where,
when等也可以引出表语从句。常见的
表语从句有下面两种句型：
⑴"The
reason…that"：表示“原因是……”。如：
The
reason
for
leaving
was
that
it
was
too
cold.
⑵"It
(This,
That)
is
because…"：表示“这是因为……”，“这是由于……缘故”。如：
This
is
because
iron
contains
more
carbon
than
steel.
4.
同位语从句
同位语从句表示与之同位的名词中心词的实际内容。
⑴同位语从句起进一步解释说明先行词的作用，通常由that引导。同位语从句的先行词
通常是一些抽象名词，如：appeal,
idea,
truth,
fact,
theory,
belief,
plan,
hope,
proposal,
rumor,
suggestion等。
There
is
truth
in
the
old
saying
that
necessity
is
the
mother
of
invention.
⑵由wh-疑问词引导，如：
I
have
no
idea
when
he
will
come.
It
is
difficult
to
answer
your
question
why
I
did
it.
⑶由名词性关系词引导，如：
Fame
and
fortune—what
others
sought
after
with
zest—was
all
rubbish
to
him.
⑷注意同位语和that引导的定语从句的区别：that在同位语从句中只起引导从句的作用，
本身并无意义，也不在句子中担当任何成分；而定语从句的that既引导从句又充当句子成分。
The
news
that
he
intended
to
come
gave
us
much
pleasure.（同位语从句，that不作句子成
分。）
He
is
the
best
speaker
that
addressed
the
meeting.（定语从句，that在从句中作宾语，指代
的先行词是主句中的主语。）