什么是会话密钥，有什么特点？

从对话后的选项中选出能填入空白处的最佳选项,选项中有两项为多余选项。

(Tim and Alan are looking at some pictures of a holiday.)

Tim:  Alan, do you want to see the pictures of my holiday in Italy?

Alan;  __1__

Tim:  Ah, the holiday was great! The food was great! The wine was great! __2__

Alan:  Why was that?

Tim:  Those Italians are crazy drivers! I don't want to think about it.

Alan:  OK. __3__

Tim:  Yes, so here's a picture of the Leaning Tower of Pisa!

Alan:  Incredible!

Tim:  __4__. We climbed to the top!

Alan:  How is your Italian?

Tim:  Not very good. But many Italians speak English very well. I was impressed! Oh, this is a land of

        fashion, too. __5__

Alan:  Well, I'm so jealous(嫉妒)…

A. I'd recommend Italy anytime!

B. It was raining that day, but it was still wonderful.

C. But the traffic was horrible!

D. Oh, these ones are nice.

E. Sure, what was it like?

F. Let's return to the good parts.

G. That's an old bridge in Florence.

中药所具有的辛、酸、苦、甘、咸不同的药味称为（）

A.四气

B.五味

C.归经

D.升降浮沉

E.毒性

高血压急症时下列哪项药物可以选用()

A．硝普钠

B．血管紧张素转化酶抑制剂

C．硝酸甘油静滴

D．硝苯地平舌下含服

E．以上均不对

以下叙述中正确的是( )。

A．用C程序实现的算法必须要有输入和输出操作

B．用C程序实现的算法可以没有输出但必须要有输入

C．用C程序实现的算法可以没有输入但必须要有输出

D．用C程序实现的算法可以既没有输入也没有输出

我国农区集中于（）。

A.西北部地区

B.中原和东部地区

C.东部地区

D.西南地区