是非谓语的题1.When I hurried to the airport,the plane was starting

D
start 后面既可以to do,也可以doing,当主语是没有生命的东西时,用to do
C
这个是不定式中所谓的有do 不带to 的结构,前面又the first thing we did.,的did 了,所以后面的to 就省略了
翻过来也一样：Wait is what I can do now
What I can do now is wait.
还有其他几个这种情况的词组和句型
can't but do
have nothing to do but do
do nothing but do
be powerless to do anything but do
There is nothing to do but do