问题 单项选择题 A1/A2型题

治疗增益比(TGF)在下列情况下,放射治疗最有价值的是()。

A.TGF=0.1

B.TGF=1

C.TGF=0.5

D.TGF=2

E.TGF=3

答案

参考答案:E

解析:一般将放射线对肿瘤与正常组织的不同生物效应之比称作治疗增益比。治疗增益比越大,放射治疗越有价值。放射治疗的基本目标是努力提高放射治疗的治疗增益比。

单项选择题
阅读理解

阅读理解。

     I don't think there is anything wrong with your blood. The key to your problem is that long nap (打盹,

小睡) after dinner.

     If you didn't sleep for hours during the early part of the evening, you would be more ready to sleep at

bedtime. If you didn't nap after dinner, you would not want to stay up so late, and you would not feel the

need to take a sleeping pill. The pill is still working in your system when you get up in the morning. This

helps account for the fact that you feel tired all day.

     You should get out of the habit of sleeping during the evening. Right after your evening meal, engage in

some sort of physical activity-a sport such as bowling, perhaps. Or get together with friends for an evening

of cards and conversation. Then go to bed at your usual time or a little earlier, and you should be able to get

a good night's rest without taking a pill.

     If you can get into the habit of spending your evenings this way, I am sure you will feel less tired during

the day. At first it may be hard for you to go to sleep without taking a pill. If so, get up and watch television

or do some jobs around your house until you feel sleepy. If you fall asleep and then wake up a few hours later,

get up but do not take a sleeping pill. Read a while or listen to the radio, and make yourself a few hours' sleep

that night, you will feel better in the morning than you usually feel after taking a pill. The next night you will

be ready to sleep at an earlier hour. The most important thing is to avoid taking that nap right after dinner and

avoid taking pills.

1. According to the writer, it is difficult for you to go to sleep because _____.[ ]

A. you get the habit of staying up late

B. you haven't taken sleeping pills

C. you sleep for hours after dinner

D. you fail to do some exercises

2. Which of the following is NOT true if you want to get out of the habit of sleeping during the evening? [ ]

A. Go to bed earlier than usual.

B. Talk with friends after dinner.

C. Stay with friends after dinner.  

D. Do some physical labor.

3. You feel tired all day probably because _____. [ ]

A. you stay up too late

B. you get up too early in the morning

C. you take sleeping pills

D. you wake up too frequently at night

4. We may infer that the author is most probably a _____.[ ]

A. doctor   

B. reporter   

C. scientist

D. professor