Probably Centimeters
Inches.
Miles.Miles.Miles.Miles.
The basic metric unit for length is the metre. Rivers would be measure in kilometres (1,000s of metres)
centimeters or cm in the metric system or SI and in the customary inches or in.
what is the customary unit of length
Seconds
It depends on what you want to measure. Their mass or size?
Metre (for its length). Kilometres per hour (speed) Tonnes (Mass)
Cm
Pint.
Either inches or millimetres Or centimetres.
A customary unit of length, which has 4 letters and starts with m, is mile.