A ruler
What metric unit would you use to measure a computer keyboard
meters
Kilograms
Litres
It would probably be miles.
What measure of units would you use to measure the thickness of a phone book
Meters
one page of a phonebook is measured in mm. unit thickness of a phone book is cm
Don't no
Yards if you work in imperial units or metres if you work in metric units
I would use meters
There is only one metric system. The relevant units, within that system would be millimetres.