单项选择题
A.主线系B.第二辅线系C.第一辅线系D.柏格漫线系
A.3P0,1,2,3S1 B.3P0,1,2,1S0 C.1P1,3P0,1,2 D.3S1,1P1
A.0 B.2.14×10-3 C.2.07×10-3 D.3.42×10-2