题型:选择题 如图所示是单摆做阻尼运动的位移-时间图线,下列说法中正确的是( )A.摆球在P与N时刻的势能相等B.摆球在P与N时刻的动能相等C.摆球在P与N时刻的机械能相等D.摆球在P时刻的机械能大于N时刻的机械能 查看答案
题型:选择题 ---Any news about Bill Clinton? ----He left power three years ago and has a little now and a little then been ______.A.heard of sinceB.heard sinceC.heard beforeD.heard of before 查看答案