A.它們的壽命應(yīng)該相同 B.90%軸承的壽命應(yīng)該相同 C.基本額定壽命相同 D.它們的壽命各不相同
A.N207/P4 B.6207/P2 C.5207/P6 D.3207/P5
A.90% B.95% C.99% D.80%