. I __________all the cooking for my family, but recently I’ve been too busy to do it.

A．will do

B．do

C．am doing

D．had done

如图所示，用细线拉着小球向上做加速运动，小球、间用弹簧相连，两球的质量分别为和，加速度大小为，若拉力突然撤去，则两球的加速度大小分别为=____________，=____________。