In exchange, Iran will halt nuclear enrichment above five percent in purity.

而伊朗则要保证暂停生为5%以上的浓缩铀。

When we measure the Sun's elemental abundance, we see it's roughly 75% hydrogen, 25% helium.

当我们测量太阳的元素时，我们看到大约有75%的氢、25%的氦。

Now we're gonna add in the carbon 13 abundance, this gold line.

现在我们要加上碳 13 ，这条金线。

For such weapons, a purity level of about 90 percent is required.

对于核器而言，要达到大概90%才行。

However, it is far below the purity needed to make a nuclear weapon.

不过，这个还远低于制造核器所需的。

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限制在3.67%。

Iran began enriching uranium up to 60 percent in April.

伊朗从4月份开始将浓缩铀提升至60%。

In this case, high-assay low-enriched uranium.

在这情况下，是高浓缩低铀。

Researchers around the world use this type of tool to estimate population numbers and overall abundance of species.

全世界的研究者都用这工具来估数量和物整体。

But then around 1850, right when carbon dioxide concentration started to rise, the carbon 13 abundance started taking a nosedive.

但是到了 1850 年左右，就在二氧化碳浓开始上升的时候，碳 13 的开始急剧下降。

But since mid-2019 after the U.S. withdrew from the pact, Iran has pushed enrichment levels back up to 20 percent.

但自2019年年中美国退出该条约后，伊朗已将浓缩铀水平推高至20%。

So we're monitoring periodically the abundance and the diversity of the rivers.

因此，我们定期监测河流的和多样性。

We found it was very significantly higher in abundance in the gut after the marathon.

我们发现在马拉松比赛后，它在肠道中的明显更高。

So, at this point, the elemental abundances were locked in.

所以，在这一点上， 元素被锁定了。

How do scientists predict something like the relative  abundance of elements in the universe?

科学家如何预测宇宙中元素的相对？

But why are astronomers so curious about the abundance ratio?

但为什么天文学家对比率如此好奇？

They've gone up to what the scientists call 60 percent enrichment.

他们已经提升到了科学家所说的60%。

Now we're going to add in the carbon 13 abundance, this gold line.

现在我们将添加碳13, 这条金线。

Remember, you need about 90% enrichment to get to a bomb.

记住，你需要大约90%的 enrichment（）才能制造出炸弹。

For each patient, they identified the most abundant or interesting clones.

对于每位患者，他们识别了最高或最有趣的克隆。