单选题 Technically, any substance other than food that alters our bodily or mental functioning is a drug. Many people mistakenly believe the term drug refers only to some sort of medicine or an illegal chemical taken by drug addicts. They don"t realize that familiar substances such as alcohol and tobacco are also drugs. This is why the more neutral term substance is now used by many physicians and psychologists. The phrase substance abuse is often used instead of drug abuse to make clear that substances such as alcohol and tobacco can be just as harmfully misused as heroin and cocaine.
We live in a society in which the medicinal and social use of substances (drugs) is pervasive: an aspirin to quiet a headache, some wine to be sociable, coffee to get going in the morning, a cigarette for the nerves. When do these socially acceptable and apparently constructive uses of a substance become misuses? First of all, most substances taken in excess will produce negative effects such as poisoning or intense perceptual distortions. Repeated use of a substance can also lead to physical addiction or substance dependence. Dependence is marked first by an increased tolerance, with more and more of the substance required to produce the desired effect, and then by the appearance of unpleasant withdrawal symptoms when the substance is discontinued.
Drugs (substances) that affect the central nervous system and alter perception, mood, and behavior are known as psychoactive substances. Psychoactive substances are commonly grouped according to whether they are stimulants, depressants, or hallucinogens. Stimulants initially speed up or activate the central nervous system, whereas depressants slow it down. Hallucinogens have their primary effect on perception, distorting and altering it in a variety of ways including producing hallucinations. These are the substances often called psychedelic (from the Greek word meaning mind-manifestation) because they seemed to radically alter one"s state of consciousness.

单选题 "substances abuse" (line 4, paragraph 1) is preferable to "drug abuse" in that ______.

A、 substances can alter our bodily or mental functioning if illegally used
B、 "drug abuse" is only related to a limited number of drugtakers
C、 alcohol and tobacco are as fatal as heroin and cocaine
D、 many substances other than heroin or cocaine can also be poisonous

【正确答案】 D

【答案解析】[解析] 此题为细节理解题。根据题干关键词定位到第一段，第一段主要说明substance意义比drug更宽一些，可以避免歧义，而drug abuse通常被理解为毒品上瘾，而实际上这里drug是广义上的substance。因而D为答案。

单选题 The word "persuasive" (line 1, paragraph 2) might mean ______.

A、 widespread
B、 overwhelming
C、 piercing
D、 fashionable

【正确答案】 A

【答案解析】[解析] 此题为猜词题，也可以视为推理题。根据单词定位到文章第二段。第二段提到咖啡提神、喝酒社交等，都说明这类物质在生活中很常见，到处可见，因而该物质是“普遍存在的”，答案为A。

单选题 Physical dependence on certain substances results from ______.

A、 uncontrolled consumption of them over long periods of time
B、 exclusive use of them for social purposes
C、 quantitative application of them to the treatment of diseases
D、 careless employment of them for unpleasant symptoms

【正确答案】 A

【答案解析】[解析] 此题为细节定位题。根据题干可以定位到第二段。文中提到反复使用一种物质可能产生身体依赖，因而答案为A。

单选题 Which of the following statement is CORRECT?

A、 Substances which trigger changes in body and psychology are drugs.
B、 Substances widely used in treatment or social activities are seen as drugs.
C、 If a person needs larger amount of some substance and has unpleasant withdrawal symptoms, physical dependence would arise.
D、 In social occasions, alcohol and smoking should be forbidden in that people tend to illegally use them.

【正确答案】 C

【答案解析】[解析] 选项C可定位到文章第二段最后两句话。

单选题 From the last paragraph we can infer that ______.

A、 stimulants function positively on the mind
B、 hallucinogens are in themselves harmful to health
C、 depressants are the worst type of psychoactive substances
D、 the three types of psychoactive substances are commonly used in groups

【正确答案】 B

【答案解析】[解析] 文章最后一段提到三种能够影响中枢神经系统并改变感觉、情绪和行为的药物，这三种药物都属于对人身体有害的，迷幻剂就是其中之一，它影响人的感知，可以产生幻觉。所以答案为B。