题目

-- Anything special in today’s papers? -- Yes. “Confidence is more important than gold” by Premier Wen     as a headline in many of today’s newspapers. A. is used     B. are used         C. has used         D. have used 答案：A如图所示，一个劲度系数为k的弹簧竖立在水平地面上，将一个质量为m的物体放在弹簧顶端，使弹簧做弹性压缩，物体静止时，弹簧的压缩量为（g为重力加速度，不计弹簧重力）（　　）A．kmgB．kmC．mgkD．kmg