2. 外语
  3. Technically, any substance other than food that alters our bodily or mental functioning is a drug.Many people mistakenly believe

Technically, any substance other than food that alters our bodily or mental functioning is a drug.Many people mistakenly believe

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问题     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 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 manifesting") because they seemed to radically alter one’s state of consciousness.  
From the last paragraph we can infer that______.
选项 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
答案B
解析 从文章最后一段的内容可知，通过影响中枢神经系统来改变人的感觉、情绪和行为的药物(物质)被称作精神活性物质；这类物质一般分为兴奋剂、镇静剂和幻觉剂；兴奋剂主要有加快或激活中枢神经系统的作用，而镇静剂却刚好于之相反：使其减缓；幻觉剂主要作用于人的感觉，以多种方式(包括制造幻觉)扭曲和改变知觉；这些就是通常被称作迷幻剂的物质，因为它们似乎彻底改变了一个人的意识状态。据此可知，在三种对神经系统起作用的物质中，兴奋剂和镇静剂影响人的中枢神经系统，而幻觉剂却改变人的知觉、情绪和行为，显然对人的身体更有害。B项与文章的
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