单选题When the heat load begins to increase, the needle valve of an expansion valve will（）Amove in an opening directionBmove in a closing directionCeither open or closeDnot move at all
单选题
When the heat load begins to increase, the needle valve of an expansion valve will（）
A
move in an opening direction
B
move in a closing direction
C
either open or close
D
not move at all
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