单选题Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?（）ACopperBCopper and carbonCCarbonDBronze
单选题
Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?（）
A
Copper
B
Copper and carbon
C
Carbon
D
Bronze
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解析：
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