以下选项中合法的用户标识符是（ ）。A．long B．_2Test C．3Dma

Dear Laura,

Thanks for your message. Yes, I’m having  a great time on my exchange program in France. It’s even  better  than I thought it would be. I was a bit nervous before I   arrived  here, but there was no reason to be. My host family is really nice. They go out of their way to  make  me feel at home. And you  wouldn’t  believe how quickly my French has improved! I’m very comfortable  speaking  French now. Although I still make lots of mistakes, it doesn’t bother me like it used to. My  biggest  challenge is learning how to behave at the dinner table. As you can imagine, things are really different from the way they are at home.  For example, you’re not supposed to  put  your bread on your plate. You’re supposed to put it on the table! I thought that was pretty strange at first, but now I’m used to it. You’re not supposed to eat  anything  with your hands except bread, not even fruit! (You have to cut it up and eat it with a fork). Another thing is that it is very rude to  say  you’re full. If you don’t want any  more  food, you should just say, “It was delicious.” Also, it’s rude to put your hands  in  your lap. You should always keep your hands ,but not your elbows, on the table. I have to say, I find it difficult to  remember  everything, but I’m gradually  getting  used to things and don’t find them so strange any more. I’ll write soon and  tell you more about life in France. Hope you’re having a good school year.

Wang Kun

小题1:How was Wang Kun before  she arrived in France?

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小题2:Why did she have no reason to be nervous?

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小题3:How has her French improved?

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小题4:What  is  one particular challenge she is facing?

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小题5:What does she find surprising?

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Venturi面罩的吸入氧浓度范围为（）。

A.21%～30%

B.24%～50%

C.21%～40%

D.30%～60%

E.24%～100%

补间铺作/平身科

俄罗斯目前主要的电视机构有（）

A．俄罗斯公共电视台

B．俄罗斯电视台

C．2×2电视台

D．俄罗斯大学电视台

E．文化电视台

空间分集是利用场强随空间的随机变化实现的。设参数η与实际天线高度h和天线间距D的关系为：η=h/D。对于水平间隔放置的天线，一般认为η≤（）时，可满足两路信号不相关性要求，可得到较好的空间分集增益。（）

A、5；

B、10；

C、20；

D、40。