单模波长1550nm,A级衰耗系数是()。
A.0.22db/km
B.0.23db/km
C.0.24db/km
D.0.25db/km
参考答案:A
早霜冻
Chafing gear is normally used().
A.for portable fenders
B.for ground tackle
C.on the inside of the hawsepipe
D.on mooring lines