The pact had allowed Iran to enrich uranium at a 3.67 percent concentration level.

该核条约允许伊朗浓缩铀丰度限制在3.67%。

Type C is the " baseline" plasma sodium concentration level is set lower than normal.

C型指血浆钠离子浓度的阈值低于正常值。

Your brain requires both of those things to remain alert, so your concentration levels will most likely dip as your brain activity slows.

你的大脑要保持清醒两者都需要，因此当你的大脑运作慢下来了，你的专注程度极可能下滑。

It might only take a minute to grab that snack, but our brains are weird and don't actually get back to that peak concentration level very easily.

你可能只需要一分钟就能吃到零食，但我们的大脑很奇怪，实际上不太容易恢复到最集中的水平。