A seesaw is an example of a first class lever The fulcrum, which is the part of the lever that does not move, is in the middle. The resistance, which is the weight (person) you are trying to lift is at one end. The effort, which is the force applied to the lever, is the person sitting on the other end.
Pyrethrin, You should know this lol
A carrier could be a person that is infected with a disease and agent but doesn't show any symptoms of it. there is a genetic carrier which is a person or an organism that inherited a trait or mutation through genetics but doesn't show any symptoms
