问题 单项选择题

(22) 应用服务将主机变为远程服务器的一个虚拟终端。在命令方式下运行时,通过本地机器传送命令,在远程计算机上运行相应程序,并将相应的运行结果传送到本地机器显示。

A.E-mail

B.FTP

C.WWW

D.Telnet

答案

参考答案:D

解析:[要点解析] E-mail是使用较为广泛的一类Internet服务,以文本形式或HTML格式进行信息传递,而图形等文件可以作为附件进行传递。 FTP是用来在计算机之间进行文件传输的。利用该服务不仅可以从远程计算机获取文件,而且还可以将文件从本地机器传送到远程计算机。 WWW是目前Internet上非常丰富多彩的应用服务,其客户端软件称为浏览器。目前较为流行的 Browser/Server网络应用模式就以该类服务作为基础。 Telnet应用服务将主机变为远程服务器的一个虚拟终端。在命令方式下运行时,通过本地机器传送命令,在远程计算机上运行相应程序,并将相应的运行结果传送到本地机器显示。

比较题
填空题

Seasick Try Controlling Your Breathing


If you get seasick easily, you may prepare for boat rides with pressure-point bracelets, ginger, or a prescription skin patch. (1) The technique presumably works because it helps control gravity sensors in the abdomen-a lesser-known input to our fine-tuned balance system.
(2) The inner ears sense motions of the head; the eyes see where the head is; and tiny sensory organs in muscles and tendons sense where the rest of the body is. More recently, researchers have realized that sensors in many other parts of the body also play a role: in the abdomen, the lower organs, and even blood vessels. (3) But if one or two don’t match up, the brain gets confused and we become nauseated.
Scientists knew the most sickening motions closely match the rate of natural breathing; they also knew that people naturally tend to breathe in time with a motion. (4)
Researchers from Imperial College London enlisted 26 volunteers to sit in a tilting, rocking flight simulator and coordinate their breathing in various ways with the motion. (5) The natural tendency was for volunteers to inhale on every backward tilt, in rhythm with the rocking. (6) They felt even better if they breathed slightly faster or slower than the cyclic heaving of the chair; using that technique, the time until onset of nausea was 50% longer than during normal breathing.
(7) Abdominal sensors are known to send motion signals to the brain more slowly than those in the inner ear because they’re farther away from the brain and because abdominal organs have more mass, which means they resist movement a tiny bit longer. (8) But if the diaphragm opposes gravity-induced stomach motions with controlled breaths, there is less sensory conflict and less nausea. "This technique is very good for mild everyday challenges," says medical research scientist Michael Gresty, a member of the study team. "it’s completely safe, and it’s not a drug."
A. But if the subjects exhaled on every backward tilt, they didn’t get sick as quickly.
B. As long as all of these sensors send matching signals to the brain, we feel oriented.
C. Now there’s one more remedy: timing your breathing to counteract the nauseating motion.
D. So why do these tactics work
E. The brain is traditionally thought to sense body position in three ways.
F. The time lag between the two types of sensors creates a mismatch that builds up in the brain and makes us gradually sicker, the researchers say.
G. The tests lasted up to 30 minutes, or until subjects felt moderately sick.
H. But no one had ever tested whether breathing out of time with a motion could prevent nausea.