The millimetre is a unit of length.

毫米是长度单位。

The diameter of the ball is 30 millimetres.

球的直径是30毫米。

It's hard to spot the bug, which is only a few millimetres long.

肉眼难以发现这只只有几毫米长的虫子。

This is a tiny little transparent pill, about 20 millimetres long.

这是一个小小的透明药丸 大约20毫米长

The bugs, which are less than a millimetre long, feed on scales of human skin and produce allergens which are easily inhaled during sleep.

这些体长不超过一毫米的虫子以人类皮肤的鳞屑为食，并且产生的过敏原在睡眠时很容易被吸入。

So, a sixty millimetre diameter pebble.

所以，一个60毫米直径的卵石。

One millimetre to the left and who knows?

往左一毫米呢？谁知道呢？

He shaved a millimetre off the block.

他把木头削去一毫米。

The deviation is reduced to one millimetre .

偏差减为一毫米。