Question

which two ways are used by the body to fight invaders? change invaders into something useful destroy invaders once they are inside ignore invaders until they have finished their work block invaders from entering the body

Explanation:

The body's immune - system can block invaders from entering (e.g., skin as a barrier) and can destroy invaders once they are inside (e.g., white blood cells attacking pathogens). It does not change invaders into something useful or ignore them.

Answer:

destroy invaders once they are inside
block invaders from entering the body