单项选择题
A.金丝 B.铜丝 C.银丝 D.铂丝
A.30%~70% B.20%~80% C.40%~60%
A.101.325kpa B.102.25kpa C.100.325kpa
A.阿基米德定律 B.牛顿定律 C.欧姆定律
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