______the students clean their classroom every day yes,they clean them after school

问题描述:

______the students clean their classroom every day yes,they clean them after school
A.Do
B.Are

Awhy?clean 是动作动词的原形,加上do这个助动词,共同做了谓语动词,do提前后,句子变为一般疑问句;而are clean是两个动词原形连用,语法是不允许的,没有这种时态。