concentration of production

例句：

1. 1. The scientist needs to concentrateon his research.
   科学家需要专注于他的研究。
2. 2.The oil is very concentrated in the bottle.
   油瓶里非常浓稠。
3. 3. The concentrationof the solution is 0.5%.
   溶液的浓度是0.5%。