硅晶体二极管与锗晶体二极管的导通压降分别为（）A、0.7V；0.3V B、0.2V；

补全对话

        根据对话内容，从对话后的选项中选出能填如空白处的最佳选项。选项中有两项为多余选项。

—Debbie! I can't believe it!I haven't seen you for ages.

—Dorothy! it's really a nice surprise!     1    

—pretty good.

—      2     

—I wish I could. But I'm on my way out. I have to be in the city in an hour.

—      3    

—there's a lot of traffic and I really have to get going. You know where I live — why don't you drop in

one evening?

—I'll do that.       4      let's keep in touch.

—I'd really like to. I'll talk to you soon, Debbie. I'm glad I ran into you.

—     5    

A. take care.

B. How are you?

C. Where have you been?

D. Can you join me?

E. Come on. Just for a minute.

F. And you should feel free to call or visit me.

G. It's been a whole year since we saw each other last time.

胸腔渗出性积液都是感染性积液。

小吴30岁，现在是中国某保险公司人力资源部的职员，请你根据有关劳动力市场的知识对下列问题加以分析

小吴所在的保险公司还没有建立工会组织，那么他是处于()的劳动力市场。

A．有组织

B．无组织

C．内部

D．外部

DWDM系统中不同波道OTU可以互换的是（）。

A.发送端OTU 

B.中继型OTU 

C.接收端OTUD 

D.收发合一型OTU

氧气瓶使用注意事项有哪些？