Indicate valleys, hills, steepness and gentleness of slopes.
The answer is SALIVA Carbohydrate digestion starts in the mouth and protein digestion starts in the stomach. The digestive system fuels the cells and the excretory system rids the body of the cells' waste.
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They are negative, and they repel.
The left is negative and the right is positive, so they attract. </span>
An apple has the ability to change color when exposed to air is a chemical property.