赤道穿过非洲的气候类型有[ ] A、热带雨林气候 　 B、热带沙漠气候 C、

在空白处填入适当的句子补全对话。

A: What can I do for you?

B: Yes, please. __1__ But what kind of flower shall I buy, roses or carnations (康乃馨)? She likes red

     roses best while today is Mother's Day.

A: I think carnations are special and better today. They show happiness, sweetness and love. They are for

     mothers.

B: All right. Can I have a look at those carnations?

A: Sure.__2__ 

B: Red.

A: What about these?

B: Great.__3__ 

A: 30 yuan.

B: OK.__4__ Here is the money.

A: Thank you. Here's the change and a card from our shop to your mom. Best wishes to her!

B: __5__ 

The children had a good time _________Christmas Eve.[ ]

A. in                    

B. at

C. to                    

D. on

证券投资的系统风险包括( )。

A．利息率风险

B．违约风险

C．流动性风险

D．期限风险

如图所示，有一辆汽车满载西瓜在水平路面上匀速前进。突然发现意外情况，紧急刹车做匀减速运动，加速度大小为a，则中间一质量为m的西瓜A受到其他西瓜对它的作用力的大小是

A．m

B．ma

C．m

D．m(g+a)

原发性疱疹性口炎最多见于哪一个年龄段（）

A.4－6月

B.6月－2岁

C.6岁以下

D.20－50岁

E.60岁以上