The purpose of taking notes is to ____________.
A:remind you of where to have new shoes
B:help you find the way of running that fits you
C:take a rest between running days
D:help you do some research on exercise
如图所示,重为100N的物体A在水平拉力F的作用下,沿水平面以0.4m/s的速度作匀速直线运动,弹簧测力计的示数为5N。不计滑轮、绳子、弹簧测力计的重力,忽略绳子与滑轮间的摩擦。则 ()
珍珠形成的原因是( )
以a、b、c为边,不能组成直角三角形的是( )
以下对南、北美洲的叙述正确的是( )