题目

 Professor Williams keeps telling his students that the future ______to the well-educated. A. belongs      B. is belonged C. is belonging       D. will be belonged 答案：A设在宇宙间有一个大体的密度为ρ，该天体的第一宇宙速度达到光速c．万有引力常量为G，求： (1)该恒星的半径R． (2)该恒星表面的重力加速度g．