挖坑：Do you know the difference of dose&dosage？Drain&drainage？

The words dose and dosage don't mean the same thing.

A dose is an amount of medication you take at one time. Doses are usually measured in metric mass units such as milligrams.

The dosage is a set of instructions for how to take the medication. It includes how much to take, when to take it, and how long to take it.

BTW， do you know the difference of drain and drainage？