题目

—A child's behavior is most easily influenced by his parents. —True. That's ________ we should set a good example to our kids. A . why B . when C . whether D . where 答案：A一辆重6×104N的载重汽车，以36km/h的速度驶上一个长为100m的斜坡，已知汽车的牵引力为4.8×103N，求：（1）汽车从坡底升到坡顶所需的时间  （2）汽车的牵引力做的功  （3）汽车发动机的功率．