We thought___ necessary to take a map with us when___.

题目

We thought___ necessary to take a map with us when___.
We thought___ necessary to take a map with us when___.
A.it's ; travel
B.it ; to travel
C.it; traveling
D.it was ;to travel
理由
尽快!

答案

C
it做形式主语
when travelling=when we travel 对时间状语当前后主语一致的时候可以省略主语用动词的现在进行时来表达