A:CO2或SO2通入CaCl2溶液中
B:过量CO2通入澄清石灰水中
C:过量SO2通入Ba(OH)2溶液中
D:过量CO2通入Na2SiO3溶液中
如图所示,物体和动滑轮的总重力为200N,当物体匀速上升的高度为2m时,绳子移动的距离为____m,若滑轮组的机械效率为80%,则动滑轮重____N.(绳子的重力、绳子与滑轮各处的摩擦均忽略不计)
—Jack ________ride a motorcycle to work.— Yes, but now he ________ there as motorcycles are not allowed on our city streets.