What do you call the Opening(s) in your instrument that help Project Sound?

Suppose that you are in a room with 3 doors and a crack in the ceiling for light. that is all. the doors each have a sign on them that says what there is behind them. door #1. a pool of corrosive acid. door #2. a crocodile that hasn't eaten in 8 months. door #3. a solar "oven". a giant lens that focuses all the sunlight at the entrance of the door. you must choose a door, which door do you choose?

Slurping is good table manners in what country?

Identify the expression 8 + 8 + 8 + 8 as a numerical expression or a variable expression. for a variable expression, name the variable.