奠定近代化学基础的是[ ] A．门捷列夫发现元素周期律 B．火的发现和利用 C．

Jack’s brother bought a magazine called Choice. It introduces to its readers information about all kinds of products like cameras, computers, cars, etc. This information helps them make the best choice when they buy something.

Jack borrowed his brother’s magazine when he needed a new computer. “I’ll read about all the different computers,” he said, “And I’ll choose the best one.”

ThinkPad G450M-T4300: This computer comes with lots of good software. However it does not have much memory and is rather slow. At $3,600, it’s not very good value for money.

HP CQ40-506AX: This is the most expensive computer we tasted. However it is also the most

reliable(值得信赖的). It is very fast and has lots of memory. Though it’s 600 dollars more expensive than ThinkPad G450M-T4300, it is worth the extra money if you can afford it.

The Acer A175-78: At only $2,600, this is the cheapest computer we tasted. It has plenty of memory and is quite fast. However, it “crashed” twice while we were testing it and we cannot recommend(推荐) it for reliability.

Jack choose HP CQ40-506AX. “I know it’s expensive, brother,” he said. “But it will last me a long time and do everything I want it to do.”

以下哪个是正确的Ethernet物理地址( )

A．00-60-08

B．00-60-08-00-A6-3 8

C．00-60-08-00

D．00-60-08-00-A6-38-00

有关硬脊膜外隙的叙述正确的有（）

A.有脂肪组织、静脉丛和脊神经根

B.腔内为正压

C.向上与颅内相交通

D.位于硬脊膜与椎管内面骨膜之间

E.富含脑脊液

试述失血时机体维持血量相对稳定的调节机制。

完整的沟通过程包括输出者、信息、渠道、干扰、反馈等五个主要因素。