单项选择题
A.应先合后拉 B.应先拉后合 C.两者皆可 D.视系统运行方式而定
A.不超过0.2% B.0.2%~0.5% C.0.5%~0.8% D.0.8%~1%
A.0.5S B.1.0S C.20S D.15S
A.100 B.105 C.110 D.115
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