destroying something is a kind of method for getting rid of something & the immune system gets rid of bacteria once they have invaded the body ->  the immune system destroys bacteria that has invaded the body  white blood cells are a part of the immune system & white blood cells are a kind of cell ->  white blood cells are a kind of cell that is part of the immune system  the immune system destroys bacteria that has invaded the body & white blood cells are a kind of cell that is part of the immune system ->  white blood cells are a kind of cell that is part of the immune system which destroys bacteria that has invaded the body  white blood cells are a kind of cell that is part of the immune system which destroys bacteria that has invaded the body & a type of cell destroys bacteria that enters the body -> white blood cells destroy bacteria that enters the body