Occurring singly; not one of a pair, as a vein or muscle.

不成对的单个存在；而非一对中单个的，如静脉或肌肉。

youdao

Occurring singly; not one of a pair, as a vein or muscle.

不成对的单个存在；而非一对中单个的，如静脉或肌肉。

youdao