A.一級負(fù)荷中特別重要負(fù)荷 B.一級負(fù)荷 C.二級負(fù)荷 D.三級負(fù)荷
A.0.1%~0.2% B.0.2%~0.3% C.0.25%~0.5% D.0.6%~0.7%
A.0.50~0.70 B.0.70~0.80 C.0.80~0.90 D.0.90~0.95