问题 单项选择题

发热开始前,先出现寒战的原因是

A.体温调定点下移

B.体温调节中枢功能障碍

C.机体过度散热

D.机体产热量不足

E.体温调定点上移

答案

参考答案:E

解析:PO/AH热敏神经元的温度反应闽值升高(斜率减小),而冷敏神经元的阈值则下降(斜率增大),调定点因而上移(例如上移到39℃)。在发热开始前,先出现战栗等产热反应,直到体温升高到39℃以上时才出现散热反应。只要致热因素不消除,产热和散热过程就继续在此新的体温水平上保持平衡。这就是说,发热时体温调节机制仍在工作,但由于调定点上移,体温升高到高于正常的水平。由于环境温度过高而引起机体中暑时,体温也升高,但这并不是因为体温中枢调定点的上移,而是由于体温调节中枢本身的功能障碍所致。

阅读理解

阅读理解。

     Expo 2010 is held in Shanghai from May 1to October 31.People all over the world are looking forward

to it. Here are several golden rules on how to best plan your trip.

     Rule 1: Do your homework

     Read everything you can before going. Really study the maps. Know the pavilions. Arrive at the entrance

nearest to the things you want to see. Have a plan. It will make a big difference.

     Rule 2: Allow plenty of time

      Expo 2010 is the largest attraction event in the history of the world. It will take many days too see it.

Plan to spend from five to eight days of more seeing it.

     Rule 3: Pace yourself

     Expo is enormous.The distances are punishing. It is better to spend a day seeing a single area than to

run back and forth all over the site. Remember to wear the most comfortable shoes. Never mind what

they look like.

     Rule 4: Get going in May

      At many Expos the crowds are smaller in May and in early June than any other time. And beware the

last two weeks. During every Expo, people delay their visits and then in early October they suddenly

realize. "Expo will close soon! I haven't seen it!" As a result, the last several weeks usually have the most

crowed days of the entire Expo.

     Rule 5: Find out what everyone else is doing - and do the opposite. If you don't like large crowds and

long lines, do the opposite.

     Here is an example: Most people go on Saturdays or on holidays. So avoid Saturdays and holidays. Go

on weekdays when most people are at work.

     Rule 6: Turn up

     Expo 2010 is the largest celebration in China's history-am amazing once -in-a-lifetime event. When it is

gone and it will never be seen again. So whatever you do, don't miss it!

1. Expo 2010 will last _____. [ ]

A. five to eight days

B. several weeks

C. six months

D. a year

2. According to Rule 4, you'd better not go to Expo on _____. [ ]

A. May 3

B. July 5

C. September 16

D. October 20

3. When there are lots of people waiting in line to see the most popular attractions, what's your best choice?[ ]

A. I'll wait in line as other people do.

B. I'll go back and return tomorrow.

C. I'll visit the less crowded places instead.

D. I'll sit on a bench to have a rest for about two or three hours.

4. In Rule 6 "turn up" here means _____. [ ]

A. don't miss it

B. come and see

C. make the sound louder

D. never be seen again

单项选择题