题目

In spite of numerous failures, they were determined to continue to           the experiment      with their new product.    A.conduct             B.distinguish             C.evaluate              D.remark 答案：A物体在某时刻的瞬时速度是5m/s，对此速度正确的理解是（　　）A．在该时刻的前1s内，物体的位移为5mB．在该时刻的后1s内，物体的位移为5mC．在该时刻的前0.5 s和后0.5 s内，物体的位移共5mD．若从该时刻起物体做匀速运动，则每秒内的位移是5m