The results of Huy’s eye exam show that he is nearsighted. Which explanation should Huy expect to hear? “You need convex lenses to shorten the distance that light takes to focus in your eyes.”
“You need concave lenses to shorten the distance that light takes to focus in your eyes.”
“You need convex lenses to lengthen the distance that light takes to focus in your eyes.”
“You need concave lenses to lengthen the distance that light takes to focus in your eyes.”

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).