引起疯牛病和人类克-雅病、库鲁病等的病原体是（） A.病毒（virus） B.类病毒

某国二定时期流通中实际需要的货币量为3000亿元，纸币发行了6000亿元，纸币在一定时期内平均流通2.5次，此时1元纸币的购买力相当于货币的

A．2.0元

B．l.0元

C．0.2元

D．0.25元

补全对话

A: Hello! This is Follow Me. Can I help you?

B: Yes. ____1____

A: What are your problems?

B: First of all, ____2____

A: Listen to English tapes and repeat what you hear. And keep practising.

B: ____3____

A: Listening to more tapes will help improve your listening skills.

B: What about new words?

A: First, you should try to guess the meaning of them. ____4____

B: OK. Thank you very much.

A: You're welcome. ____5____

A. I am afraid to speak English in front of others.

B. I hope your English will improve soon.

C. I can't get the pronunciation right.

D. Then you can look them up in a dictionary if necessary.

E. Keeping a diary can improve your writing skill.

F. And I can't understand the teacher when she talks to the class.

G. I have some problems with my English.

如何理解黑格尔关于艺术美本质的定义“美是理念的感性显现”

气海穴的主治作用。

视频文件的常见格式有哪些？有何特点？