Ⅰ.动名词和不定式做主语的相同点
1.不定式短语和动名词做主语时，常常为了保持句子的平衡，用it来做形式主语，如：
It
is
not
easy
to
learn
English
well.
It
is
no
use
asking
him
for
help.
2.如果主语用了不定式,表语和宾语也要用不定式;主语用了动名词,表语和宾语也要用动名词,这在英语中称为对称性,如:
To
see
is
to
believe.
=
Seeing
is
believing.
(眼见为实)
(85)It
is
better
to
stay
home
than
_A__
out.
A.
to
go
B.
going
C.
go
D.
gone
Ⅱ.动名词和不定式做主语的不同点
1.不定式做主语常表示具体的某一动作;表示泛指或一般的抽象的概念时,多用动名词,如:
(92)_B_
is
a
good
form
of
exercise
for
both
young
and
old.
A.
The
walk
B.
Walking
C.
To
walk
D.
Walk
2.在”There/It
+be+
no
use(good/help/need)”之后常用动名词做主语,而少用不定式,如:
It
/There
is
no
use
crying
over
the
split
milk.
It
/There
is
no
help
taking
this
medicine.
★但是如果该句型中用了for引出不定式的逻辑主语,就只能用不定式,如:
(93)
There
is
no
good
for
us
to
do
that
exercise.
3.不定式可以和when,
where,
how,
what,
whether等连用,在句子中做主语,宾语和表语,而动名词则不能,如:
How
to
solve
the
problem
is
a
hot
potato.
Where
to
put
the
box
seems
hard
to
decide.
Whether
to
do
it
hasn’t
been
decided.
What
to
do
next
is
up
to
you.
标签：主语,动名词,不定式
