题目

根据句意及首字母或汉语提示完成单词。 1. It isn’t s to play soccer on the road. 2. My friend has c a lot of coins(硬币). 3. Look at the white (狐狸). It’s so beautiful. 4. My grandparents live in a small but (安宁的)town. 5. Everyone thought their performance was (完美的). 答案：1. safe 2. collected 3. fox 4. peaceful 5. perfect土星周围有一颗质量为m的卫星，它绕土星的运动可视为匀速圆周运动，轨道半径为r，周期为T。已知土星的半径为R，引力常量为G。 （1）求土星的质量；（2）土星表面的重力加速度。