给下列物质加热后,生成物全部是氧化物的是[ ]
A.氯酸钾
B.碳酸钙
C.高锰酸钾
D.碱式碳酸铜
BD
—I'll tell something about the change in your job tomorrow.
—You ________ me some time earlier.
A.ought to tell
B.would have told
C.must tell
D.should have told
如右图所示,一木块在光滑水平面上受一恒力F作用,前方固定一足够长的弹簧,则当木块接触弹簧后()
A.立即做减速运动
B.在一段时间内速度仍可增大
C.当F等于弹簧弹力时,木块速度最大
D.弹簧压缩量最大时,物体加速度为零