(Q).
If using some engines requires burning fossil fuels, then what requires burning fossil fuels? Answer choices: - Fuel cells - using electricity - animals - Cooking - organisms - engines - lightning - solar power
(A).
engines

(Q).
If oxygen typifies life, then what typifies life? Answer choices: - Beauty - exercise - Energy - Color - recovery - Movement - Oxygen - Energy.
(A).
Oxygen

(Q).
If abreathing mask is used to keep smoke out of the respiratory system, then what keeps smoke out of the respiratory system? Answer choices: - Cooking - Masks - Glasses - skin - Gloves - Hats - Urea - oxygen
(A).
Masks