We can improve the shelf life of foods by chemicals, exposing foods to oxygen, or exposing foods to carbon.) ,drying, fermentation, or freezing.) is a food preservation technique that uses bacteria.

We can improve the shelf life of foods by adding chemicals to food. Fermentation is a food preservation technique that uses bacteria.

Explanation:

100% on test.

ANSWER: 1{ Adding chemicals to food | 2{ fermentation

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.