-What are they doing？-Look they on the playground.A. are running B. runs C. is r

问题补充：

---- What are they doing？

---- Look, they on the playground.

A. are running B. runs C. is running

答案：

解析：本题问句问的是现在正在做某事，所以回答语使用现在进行时，结构为be+现在分词doing，本题的主语为复数，故be用are，故本题选A。