设地球自转周期为T，质量为M，引力常量为G，假设地球可视为质量均匀分布的球体，半径为R．同一物体在南极和赤道水平面上静止时所受到的支持力之比为（   ）

绿色食品指的是（  ）

完形填空

    Bosh is a worker．He 1  very poor．He lives in a dirty small room and2about food. His friends are 3  too．One night the wind is hard and 4  is snowing heavily. Bosh5to bed early but he can't fall asleep(入睡)．He doesn't have 6 for supper. He  7 a man get in through a broken window．The man8to search the bookshelf. Bosh gets up，says to the man, “Don't waste time．I can't  9 any money in the daytime. How can you find any at10 ?”