题目

—________ will you ask for help when you get into trouble(有困难)?—My parents，I think. A . Who B . What C . Where 答案：A小明在400米的环形跑道上跑了一圈，已知他前一半时间每秒跑6米，后一半时间每秒跑4米，则小明跑后一半路程用了______秒．