<span>Alternating between running and walking is important, especially if you're not a professional runner. You should be walking from time to time to recover a bit from the strain that the running put on you, but not too much or your body starts to cool down and then you have to work all over again or you might lose energy.</span>
Because it is for school related topics. Join a chat room that allows you to say as you wish. Like your mom would say: Their house, Their rules.
Answer:
C. A tightly sealed house with an unvented water heater.
Explanation:
