He was so busy that he couldn’t help ____________ the experiment. A．doing B．do C．did D．done
2022-12-27 03:21:43 133次 2015届四川攀枝花米易县米易中学高一上第一次段考英语试卷（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
He was so busy that he couldn’t help
____________ the experiment.
|
A．doing
|
B．do
|
C．did
|
D．done
|
本题链接：
