题目

手提一挂有重物的轻弹簧竖直向上做匀加速运动，当手突然停止运动的瞬间，重物将：                                                          A．停止运动B．向上匀减速运动C．向上匀速运动D．向上加速运动  答案：D 解析:略 30、I’m sure he’s up to the job ________ he would give his mind to it.   A, only if              B. if only               C in case           D. until