下列物体的质量,可能是50g的是 ( )
A:一个乒乓球
B:一支铅笔
C:一个鸡蛋
D:一辆汽车
In western countries, when your friend offers (提供 )you something, you can accept it directly(直接地), or refuse it politely. Therefore, which situation fits the western custom?