The skin of an animal should be examined for

The skin of the animal is one of the first systems affected so it is the first indicator when an animal becomes sick. The skin of an animal should be examined for signs of disease. Examined should be the structure and the functioning of the skin. If there are some abnormalities it can be sign that the animal is sick. 

Humans can affect weathering and erosion in several ways.  humans cause  increases in acid rain and pollution, which increase the amount of  weathering  agents in the air and water, and then on land.for an easy answer: 1) acid rain2) pollution

Where are the following