下述关于重力的说法正确的是[ ]
A．物体的重力就是质量
B．重力的施力物体是地球
C．物体重力大小与形状有关
D．物体上抛时重力变小
答案：B
I shall never forget the days ________ I lived in the country with my friends. [ ]
A. that
B. which
C. when
D. at which
减小热阻的具体措施有（）条。
A.三
B.四
C.五
D.六
