Exchange of oxygen and carbon dioxide in the lungs occurs between the and the alveoli.
a. capillaries
b. bronchi
c. arteries
d. veins

Label the following as inner or outer planets; a) has 67 moons made mostly of hydrogen and helium b) has rings c)no moons, high volcanic activity d) known as the red planet, has 2 moons e) very thin atmosphere, moons or rings