- UID
- 424488
- 帖子
- 121
- 积分
- 174
- 学分
- 1176 个
- 金币
- 10 个
- 在线时间
- 33 小时
|
In order to exploring the universe, scientists have done quite a few of experiments.
The first is gravitational force, which hold you to the ground or make you fall when you uncareful.
The four known forces appeal to explained everything, and fifth force seemed unnecessary |
|