Describe how human impact on the environment can be positive or negative.

Explanation:

Positive : creating forest reserves, proper recycling of waste, etc.

Negative : Bush Burning, improper waste disposal, etc

substitution is the answer in this case

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.