每条触手大约两毫米长。

Each tentacle is about two millimeters long.

youdao

那个生物是一只很小的蜈蚣，只有10毫米长。

The creature is a tiny centipede, just 10 millimetres long.

《柯林斯英汉双解大词典》

这些水母只有1毫米长。

These jellyfish were only one millimeter long.

youdao

00 times electrode is only 1 mm long that penetrates just the most outer layers of the outer regions of your brain called into the distributable cortex.

00个这样的电极只有1毫米长,他们插进大脑最外层的区域的最外层,这个区域被称为分布皮层。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选