Inches (or centimeters, if you're working in the metric system).
Millimetres, centimetres or inches
Millimeters.
That would normally be measured in cm. It might also be measured in dm., but this unit is not very common in daily usage.
Grams
I would go with inches but you could measure it in centimeters.
You would measure it in centimeters.
Centimeters
Centimeters
Centimeters
Millimeters.
Millimetres, centimetres or inches
Pencil lead is very narrow. Millimeter can be used to measure it.
you would use gallons
centimeter
You could use either centimeters or millimeters, but probably centimeters.
a ruler
That would normally be measured in cm. It might also be measured in dm., but this unit is not very common in daily usage.