题型:问答题 简答题 The coach, because of the driver’s carelessness, was __________ and crashed over the cliff on such a cold December morning.A.in supportB.out of controlC.in chargeD.at the mercy 查看答案
题型:问答题 简答题 从地面以某一初速度竖直向上抛出一个小物体,若不计空气阻力,则在上升过程中 ( )A.重力对物体做正功,重力势能增大B.重力对物体做负功,重力势能增大C.物体的动能减小,机械能减小D.物体的重力势能增大,机械能增大 查看答案