The three things necessary for combustion are: A) Gas, air, ...

[RRMR]

The three things necessary for combustion are:
 
  A) Gas, air, and a burner. B) Fuel, heat, and carbon dioxide.
  C) Fuel, oxygen, and heat. D) Air, gas, and a combustion chamber.

Question 2

Large rooftop package AC units often use ________ to help draw in fresh air to meet code requirements and to cool if temperature and humidity permit.
 
  A) low pressure B) airflow C) enthalpy D) an economizer

[abctaiwan]

Answer to Question 1

C

Answer to Question 2

D

[RRMR]

YES! Correct, THANKS for helping me on my review

[scikid]

Thanks for the timely response, appreciate it