题目

One day， when Ben with Sam in the street， a motorcycle came towards Ben and knocked him down.A.is walking B.walked C.was walking D.had walked 答案：【答案】C【解析】句意：一天，本和萨姆在街上散步时，一辆摩托车朝本驶来，把他撞倒了。A. is walking散步，现在进行时；B. walked散步，过去式；C. was walking正在散步，过去进行时；D. had walked已经散步，过去完成时。when引导的时间状语从句，主从句时态要一致，主句用一般过去时，从句用过去进行时在△ABC中，已知∠C=90°，sinB=，则cosA的值是（ ）A．B．C．D．