题目

 Gorge came into the interview room and sat down at the desk, ____ to answer questions. A. preparing          B. prepared         C. prepare           D. to prepare 答案：B滑块以某一初速度从斜面底端冲上斜面做匀减速直线运动，到达斜面顶端时的速度为零。已知滑块通过斜面中点时的速度为v，则滑块的初速度为