单项选择题
A.10-6 B.10-5 C.10-4 D.10-3
A.一端为568A另一端为568B B.两端均为568A C.两端均为568B D.无标准
A.<40% B.<45% C.<50% D.<55%
A.0.2 B.0.3 C.0.4 D.0.5
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