— are they doing? — They’re .A. What run B. What running C. Who running

问题补充：

— are they doing? — They’re .

A. What, run B. What, running C. Who, running

答案：

解析：句意：他们正在做什么？他们正在跑步。what什么，who谁，run跑步，现在分词的形式是双写n加ing,故选B