问题 单项选择题

真毛细血管不具有下列哪一项特点

A.管壁很薄、通透性大
B.微动脉阻力对血流控制的作用不大
C.是血液和组织液进行物质交换的场所
D.安静时,骨骼肌中大约有20%~35%的真毛细血管处于开放状态

答案

参考答案:B

解析:[考点] 毛细血管的生理特性
[分析] 真毛细血管是组织液与血液进行交换的场所,它的数量多,管壁薄,通透性大,加上血流缓慢,有利于物质交换的进行。某一组织中,微循环的血流量与微动脉和微静脉之间的血压差成正比,与微循环中总的血流阻力成反比。因在总的血流阻力中,微动脉处的阻力占较大的比例,故微动脉的阻力对血流量的控制起主要作用。组织中的毛细血管并不都是处在开放状态,这与局部代谢有密切的关系。安静状态下,骨骼肌组织中在同一时间内只有20%~35%的真毛细血管处于开放状态。

阅读理解

Read the following text and choose the most suitable heading from A-F for each paragraph. There is one extra heading which you do not need.

A. Reasons for the use of Podcasting

B. Definition and origin of Podcast

C. Importance of Podcasting at school

D. Advantage of Podcasts over other audio media

E. Podcasts—a further step from voice recordings

F. Devices needed for Podcasting

小题1:_______

Recently a group of second-graders visited our school library to work on a “holidays around the world” project. The children created pictures showing holiday customs and then created voice recordings explaining what they drew. The incident showed very clearly the effectiveness of student-created voice recordings. Now imagine taking things one step further and creating Podcasts in a classroom setting.

小题2:________

The term Podcast refers to an audio recording, linked to the Web, that can be downloaded to a personal MP3 player. The word is created from broadcast and from iPod ---the wildly popular MP3 player from Apple.

小题3:________

Using audio with students isn’t new, of course. Teachers have used audiobooks at listening centers and recorded student voice on tape or CD for many years. Voice and music are the original media for teaching. Podcasts, however, can reach a much wider audience in a time frame outside the school days. Booktalking, an old way of getting kids excited about books, gets a tech assistance with Podcasting. Students can do some booktalking themselves; book review Podcasts seem to be another natural way for students to share what they know, providing an alternative to the book report.

小题4:________

There are a number of excellent reasons for using Podcasting. Teachers made audio Podcasts, including visuals or video clips for any content area instruction and review. Some teachers have begun to record themselves teaching important concepts; this creates an account of information online for kids to access when they’re stuck on a homework assignment. Audio and video files can also function as assessment tools. Imagine being a classroom teacher in September who can actually hear how his or her students were reading in June the school year before.

小题5:________

You don’t need an iPod to make a Podcast. If you have a computer, a microphone, and some free software, you can make a Podcast. While an MP3 player is a popular and useful gadget, your audience doesn’t need MP3 players to listen, either: your students and their families can use the computer to play back what you’ve recorded.

单项选择题