The old man with his son_______the street carefully when the traffic light was red.

The old man with his son （A.were crossing） the street carefully when the traffic light was red.当红灯亮时,那位老人正和他的儿子一起小心地过马路.时间状语为when引导的过去时,主句为过去进行时态,表示过去...答案是C这个所谓的答案肯定是错的了。across是个介词，而这里应该是填个动词作为句子的谓语。选择C项太离谱了。