So DNA is a set of instructions for how our bodies work written using a chemical code of four letters – A, T, C, G. But sometimes the code contains mistakes.

那么，DNA是A、T、C、G四种碱基编码组成的指示机体运转的遗传指令。但是有时候这些编码中会出现错误。

One word, four letters, no punctuation, no emojis, just " sure."

个词，几个，没标点，没表情，个“好的”。

Marsha, these are letters to my family and friends back at home......four letters!

玛莎，这些是给我家乡的亲友的信件......四封信！

They've got a repeating four- letter word ending with two symbols that stand for L.

现在他们找到好几个两个样符号的 四个的。

I heard that the last four letters were dubba-you, ex, why, zee.

我听到最后四个是dubba-you，ex，why，zee。

A little one—it's not like OK comes from Latin or Greek and shows ignorance on the part of someone who spells it out with four letters.

小的那个——不像“OK”来自拉丁语或希腊语，用四个出来暴露了某人的无知。

After I was able to make four letters, I would tell any boy who could write that I could write as well as he did.

在能够出四个后，我便告诉任何个会的男孩，说我能得和他样好。

And then we hear it's on City Road, then the road to the right and we see three, oh actually four letters there.

然后我们听到它在城市路，然后是路的右侧，我们看到三个，哦，实际上是四个。

It was too simple. It had just four basic components, called nucleotides, which was like having an alphabet of just four letters.

它太简单了，主要由4个被称为核苷酸的基本物质组成。这好比个只有4个的表。

The code comes out to be a fairly simple alphabet, four letters: A, T, C and G.

这个遗传密码由简单的表组成，四个，A，T，C和G （碱基）。

Four letters in three months and this is the first mention of Kathleen Johns?

三个月来四封信 这是第封提到凯萨琳琼斯的？

Imagine what it would be like if the English alphabet had four letters.

想象下， 如果英文表有四个会是什么样子。

Don’t get me too excited because I use four letter words when I get excited.

不要让我太兴奋， 因为当我兴奋时我会使用四个的单词。

And that's one four letter word that most people don't like.

那是个大多数人不喜欢的四个的词。

And it's just a cool four letter word.

这只是个很酷的四个单词。

Four letters four words. Four letters four words.

四个四个词。四个四个词。

Takeaway four, letter writing is a hobby.

第四点，信是种爱好。

The first four letters, S-E-A-M, when used on their own, form a noun.

前四个S-E-A-M单独使用时，构成个名词。

Can you fit that into your four letter code?

你能把它放入你的四代码中吗？

So all life on this planet is made in ATCGs, the four letters of DNA.

所以这个星球上的所有生命都是由 ATCG 构成的，即 DNA 的四个。