单选题The cooling water temperature （） over a period of 8 hours, and then shut down.Ashould be gradually increasedBshould be gradually reducedCshould be constantly keptDshould be varied up and down
单选题
The cooling water temperature （） over a period of 8 hours, and then shut down.
A
should be gradually increased
B
should be gradually reduced
C
should be constantly kept
D
should be varied up and down
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