You would use the unit pounds or 'lb.' Usually, when measuring the weight of anything, you would use the unit pounds. Weight is to differentiate the difference in mass from one place to another. On the moon you weigh something, on the earth you weigh something heavier. So, to compare that, we generically use pounds to identify weight. An example: 25 lb. If you were measuring mass, however, it would be grams then.
pounds
ounces
Cm
Inches.
Miles.Miles.Miles.Miles.
It is customary to use the kilogram - though that is technically not a weight, but a mass.
pounds
You would use pounds or kilograms to measure the weight of a person.
The ounce.
The appropriate scale for the measurement of the weight of an earring would the milligram. this is because the weight of an earring is so small that it would be difficult to determine it s weight while reading on a bigger scale like the kilogram.
SI . . . Newton 'Customary' . . . pound, ounce, etc.
Normally pounds or Kilograms but larger amounts could move in to tons and metric tons
Seconds
ounces
ounces
It depends on what you want to measure. Their mass or size?
Cm