仓库物资保管应做到哪些要求？
参考答案：
做到“五无”：即无丢失、无锈（腐）蚀、无霉料变质、无损坏事故、无账外物资。
---Can you tell me _______?
---With Lucy’s help.
A．when you did it so well
B．when did you do it so well
C．how you did it so well
D．how did you do it so well
DWDM系统中光放到光放之间是（）纤光路，OLP到OLP之间是（）纤光路
A.单、双
B.双、双
C.单、单
D.双、单
