组成地球上蛋白质的那20个（氨基酸）都是左旋氨基酸。

The twenty that make up the proteins on Earth are all left-handed.

youdao

组成地球上蛋白质的那20个（氨基酸）都是左旋氨基酸。

The twenty that make up the proteins on Earth are all left-handed.

youdao