问题 单项选择题

某岛上的男性公民分为骑士和无赖。骑士只讲真话,无赖只讲假话。骑士又分为贫穷的和富有的两部分。有一个姑娘,她只喜欢贫穷的骑士,一个男性公民只讲了一句话,使得这姑娘确信他是一个贫穷的骑士。另外,姑娘问任何一个男性公民一个问题,根据回答就能确定他是贫穷的骑士。

如果上述断定都是真的,下面哪项断定也一定是真的 Ⅰ.自行车不允许在高速公路上行驶。 Ⅱ.今天我的汽车仍然可能不被允许在高速公路上行驶。 Ⅰ.如果我的汽车的时速超过60公里,那么当日肯定是逢双日。

A.Ⅰ、Ⅱ和Ⅲ。

B.仅Ⅰ。

C.仅Ⅰ和Ⅱ。

D.仅Ⅰ和Ⅲ。

E.仅Ⅱ和Ⅲ。

答案

参考答案:C

解析:根据题干中的P和Q可以进行否定后件到否定前件的充要条件假言推理,由此得到结论:自行车不是在高速公路上运行的交通工具,所以,Ⅰ一定是真的。题干中的R是一个必要条件的假言命题,S是对R的前件的肯定,对必要条件的假言命题来说,前件为真,后件可能真也可能假。所以,“今天我的汽车不被允许在高速公路上行驶”有可能是真的。因此,Ⅱ一定真;Ⅲ不一定是真的,因为我的汽车时速超过60公里只是肯定了P这个充分条件假言命题的后件,不能因此推出“我的汽车不在高速公路上行驶”,也就不能推出“当日肯定是双日”。

单项选择题
阅读理解

阅读理解。

     Increasingly, Americans are becoming their own doctors, by going online to diagnose(诊断) their

symptoms, order home health tests or medical devices, or even self-treat their illnesses with drugs

from Internet pharmacies(药店). Some avoid doctors because of the high cost medical care(忧虑),

especially if they lack health insurance(保险). Or they may stay because they find it embarrassing to

discuss their weight, alcohol consumption(消耗) or couch(睡椅) potato habits. Patients may also

fear what they might learn about their health, or they distrust physicians because of negative

experiences in the past. But playing doctor can also be a deadly game.

     Every day, more than six million American thru to the Internet for medical answers-most of

them aren't nearly skeptical(怀疑的) enough of what they find. A 2002 survey by the Pew Internet

& American Life Project found that 72 percent of those surveyed believe all or most of what they

read on health websites. They shouldn't look up "headache", and the chances of finding reliable and

complete information, free from a motivation for commercial gain, are only one in ten, reports an

April 2005 Brown Medical School study. Of the 169 websites the researchers rated, only 16 scored

as "high quality". Recent studies found faulty facts about all sorts of other disorders, causing one

research team to warm that a large amount of incomplete, inaccurate(错误的) and even dangerous

information exists on the Internet.

     The problem is that most people don't know the safe way to surf the web. "They use a search

engine(工具) like Google, get 18 trillion choices and start clicking. But that's risky, because almost

anybody can put up a site that looks authoritative (有权威的), so it's hard to know whether what

you're reading is reasonable or not," says Dr. Sarah Bass from the National Cancer Institute.

1. According to the text, an increasing number of American ________. 

A. are suffering from mental disorders

B. turn to Internet pharmacies for help

C. like to play deadly games with doctors

D. are skeptical about surfing medical websites

2. Some American stay away from doctors because they ________.

A. find medical devices easy to operate

B. prefer to be diagnosed online by doctors

C. are afraid to face the truth of their health

D. are afraid to misuse their health insurance

3. According to the study of Brown Medical School, ________.

A. more than 6 million American distrust doctors

B. only 1/10 of medical websites aim to make a profit

C. about 1/10 of the websites surveyed are of high quality

D. 72% of health websites offer incomplete and faulty facts

4. Which of the following is the author's argument?

A. It's cheap to self-treat your own illnesses.

B. It's embarrassing to discuss your bad habits.

C. It's reasonable to put up a medical website.

D. It's dangerous to be your own doctor.

5. Which of the following statement is TRUE?

A. Because of health insurance, Americans like to see doctors.

B. It's fun for Americans to play doctors.

C. Recent studies showed that the Internet was not in order.

D. You can trust what you're reading on the Internet.