Opinion means a statement that states feelings and thoughts. An opinion could be: Her hair is pretty. Someone else may think her hair is ugly. It's your thought, your opinion.
only one rule, Always wear them while working on anything
This food is good.You're dumb.This book is the best I've ever read.You smell funny.
Read this old study: Langham, W. (1952): "Toxicology of Actinium Equilibrium Mixture", Los Alamos Scientific Lab.: Technical Report,...
It has been said, it is the international language, everyone can understand and appreciate.