A．力是维持物体运动的原因
B．力是使物体运动状态改变的原因
C．力是使物体运动的原因
D．力是使物体运动速度不变的原因
答案：B
—How did you find your visit to the Summer Palace yesterday?
—_________．I got separated from my 80-year-old grandparents
A．It couldn’t be better
B．I have no idea
C．Good luck to me
D．It couldn’t be worse
甲数×乙数=240，如果甲数扩大到原来的3倍，乙数不变，积是______；如果甲、乙两数同时扩大到原来的2倍，积是______．
