Question

There was nothing to do（ ） wait until he came back.

A.but B.but to 答案选A，可是but前面是to do，根据平行结构，后面也应该是but to wait 呀。为什么选A呢？

Answer 1

当but/except解释为“除了”时，如果后面跟上动词，有两种情况，一种是用to
+动词原形，另一种就是直接跟上动词原形。判定原则是这样的：
当but/except前有动词do这个词的任何一种形式的时候，在but/except后不加to，直接跟上动词原形；
当but/except前没有do这个词的时候，那么后面就要用to+动词原形。
如：He
could
do
nothing
but
wait.
He
had
nothing
to
do
but
wait.
He
had
no
choice
but
to
wait.
另外，还有几个常用的短语也要记住：
can't
but
do;
can't
hlep
but
do
这两个短语都解释为“不得不做……
can't
help
doing
情不自禁做……；忍不住做……
can't
hlep
to
do
不能帮助做某事
如：She
can't
help
to
clean
the
room
because
she's
busy
making
a
cake.
While
shopping,
people
sometimes
can't
help
being
persuaded
into
buying
something
they
don't
really
need.