The concept of a particle is only an approximation, valid in certain limiting cases.
粒子的概念只是一种近似,仅在特定极限情况下有效。
再说,义就是匡正的意思,不能以下正上,必须是以上正下。 
The dairy industry must adapt to changing consumer preferences.
Keep an open mind, accept different opinions.
对于有知识的人来说,言语是最好的展示。
Wealth should not be concentrated in the hands of a few, but should be distributed among all through fair competition.