We ( ) cotton when they arrived.

问题描述:

We ( ) cotton when they arrived.
A.were picking
B.would pick
C.are picking
D.have picked

A.首先arrived表明是过去式,when这里表示同时进行两件事,所以动词用ing形式.意思为当我们正在看卡通片的时候他回来了.强调我们正在做的那个动作