单选题The phraseheat recoveryrefers to a _____.A method of concealing the source of heatB special form of air-conditioningC supplementary hot water systemD way of reclaiming and re-using heat
题目
单选题
The phraseheat recoveryrefers to a _____.
A
method of concealing the source of heat
B
special form of air-conditioning
C
supplementary hot water system
D
way of reclaiming and re-using heat