單項(xiàng)選擇題
A.9 B.12 C.15
A.1 B.2 C.3
A.18 B.20 C.22
A.20 B.30 C.40
A.40 B.50 C.60
A.100 B.150 C.200
A.250V B.550V C.600V
A.9m B.12m C.15m
A.3‰、2.2 B.7‰、2.0 C.7‰、1.8
A.3‰ B.5‰ C.7‰
A.200 B.250 C.300