Q: What man-made substance tends to break down ozone in the stratosphere? A:
OPTIONS:
- gasoline
- steel
- plastic
- cfcs

Answer: cfcs

Q: Homes and transportation use what percent of all energy in the u.s.? A:
OPTIONS:
- twenty five
- fifteen
- forty
- half (fifty)

Answer: half (fifty)

Q: Capillaries are narrow-diameter tubes that can fit red blood cells through in single file and are the sites for the exchange of what? A:
OPTIONS:
- proteins
- fluids
- components
- nutrients

Answer:
nutrients