——Cathy, could you come to our art club tomorrow?
—— .
A:I'm sorry to hear that
B:Sure, I'd love to
C:Never mind
D:Take it easy.
如图是小红同学研究定滑轮和动滑轮特点的实验情景,下列说法正确的是( )
你会飞吗?
如图所示的杠杆,每个砝码重均为1牛顿,杠杆处于平衡状态,若在杠杆两边各减去一个砝码,则( )