For example, I am in a high-level math class that actually gives me college credits for next year.

Eggs are sold by the dozen.

Rice is sold by the kilogram.

Rice is sold by the kilogram.

They sell land by the acre.

Did you finish your class registration?

I might flunk the course.

Human physiology is a three-credit course.

Flour is sold by the pound.

The course is credited for 50 minutes.

What are the units of time?

I don't have enough credits to graduate.

I am paid by the week.

We hired a boat by the hour in the park.

As soon as we are born, the world gets to work on us and transforms us from merely biological into social units.

We sell sugar by the pound.

Shoes are sold in pairs.

The family is the basic unit of society.

Pencils are sold by the dozen.

Apples are sold by the dozen.