-I saw Jim and your brother in the park yesterday morning.-they ---- skating there,right?

问题描述:

-I saw Jim and your brother in the park yesterday morning.-they ---- skating there,right?
A.practiced B.were practicing C.have practiced D.have been practicing

选B
看见某人在做某事,用现在进行时,因为是昨天,所以用过去进行时.