Answer:
a year because it can take up to months or days
Answer:
C or D
Explanation:
When we say a furnace is “sealed combustion,” it means it draws on air from outside the house to use for burning fuel (i.e. combusting fuel). ... It's closed-off and draws air through a plastic PVC pipe that connects it to the outside. A second pipe attached to the combustion chamber sends out the exhaust
Answer:
With no "control" you have no base line to compare your results with, for whatever hypothesis your testing
Explanation:
