题目

TheCzar sent a troop of his best soldiers to Frederick William（作为对……的回报） Prussia giving the amber room to him. 答案：【1】in return for/in reward for/as a reward for7．（1）如图1所示，一个质量为10kg的铁球沿斜面滚下，请画出铁球所受重力的示意图．（g=10N/kg ）（2）如图2所示，O是支点，画出图中F1和F2的力臂．