Answer :

Milk is good for you. 
America is the most free country on Earth. 
You will get cramps if you swim right after you eat.
those are examples of Coomonplace assertion 

A commonplace assertion is a statement that people just assume is correct and applies to everyone, even though there may not be any proof to support that assertion.

For example: An apple a day keeps the doctor away.

This asserts that if you eat an apple every day you won't ever get sick, and that is certainly not true.