英语语法分析

That can happen but that's abnormal, but changes in maybe the chemistry of the backbone that holds the nucleotides together.

那可能发生的，但属于非正常的变化，但是可能主链的化学变化将核苷酸结合在一起。

Most genes average more than 1000 nucleotides.

大部分基因平均有超过1000个核苷酸。

Each color corresponds to one of four nucleotides.

每种颜色对应四种核苷酸中的一种。