Millimetres are used to measure length.

Area is measured in units squared.

Cubic metres and litres are not related.

There are 100 centimetres in 1 metre.

There are 100 metres in 1 kilometre.

There are 1000 millilitres in 1 litre.

Millimetres, centimetres and metres are all related.

Volume can only be measured in cubic metres.