原文+翻译：
Technically, any substance other than food that alters our bodily or mental functioning is a drug.
从专业角度说，除食品外，任何能改变我们生理和心理机能的物质都是药物。
Many people mistakenly believe the term drug refers only to some sort of medicine or an illegal chemical taken by drug addicts.
很多人错误地认为“药物”一词仅仅指某些药品或是吸毒者服用的违禁化学品。
They don’t realize that familiar substances such as alcohol and tobacco are also drugs.
他们没有意识到诸如酒精、烟草这些我们熟悉的物质也是药物。
This is why the more neutral term substance is now used by many physicians and psychologists.
这就是为什么现在许多内科医生和心理学家使用“物质”这个更加中性的词。
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.
他们常用“物质滥用”而不用“药物滥用”来清楚表示滥用酒精、烟草这样的物质可能如同滥用海洛因和可卡因一样有害。
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.
我们生活在一个物质（药物）在医疗和社交方面使用广泛的社会里：用来缓解头痛的阿斯匹林，用来应酬的酒，早晨用来提神的咖啡，还有定神用的香烟。
When do these socially acceptable and apparently constructive uses of a substance become misuses?
使用这些物质得到了社会认可，且显然具有积极的作用，但什么时候就变成滥用了呢？
First of all, most substances taken in excess will produce negative effects such as poisoning or intense perceptual distortions.
首先，大多数物质的过量使用都会产生负面影响，如中毒或严重的知觉错乱。
Repeated use of a substance can also lead to physical addiction or substance dependence.
反复使用一种物质可以导致成瘾或对该物质的依赖。
Dependence is marked first by an increased tolerance,
依赖的最初表现是不断增长的耐药量，
with more and more of the substance required to produce the desired effect,
要产生预期的效果需要的药剂量越来越大，
and then by the appearance of unpleasant withdrawal symptoms when the substance is discontinued.
然后是一旦中断使用就会出现难受的停药症状。
Drugs (substances) that affect the central nervous system and alter perception, mood, and behavior are known as psychoactive substances.
影响中枢神经系统，改变知觉、情绪和行为的药物（物质）被称为精神活性物质
Psychoactive substances are commonly grouped according to whether they are stimulants, depressants, or hallucinogens.
它们通常按照功能被分为兴奋剂、镇静剂和幻觉剂。
Stimulants initially speed up or activate the central nervous system,
兴奋剂主要起到加速或激活中枢神经系统的作用，
whereas depressants slow it down.
而镇静剂则减缓它的活动。
Hallucinogens have their primary effect on perception, distorting and altering it in a variety of ways including producing hallucinations.
幻觉剂主要影响人的知觉，通过多种方式扭曲或改变知觉，其中包括产生幻觉。
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.
这些物质常被认为能“引起幻觉”（psychedelic一词源于希腊语，意为“心灵显现”），因为它们似乎能彻底改变人的意识状态。
试题：
51. “Substance abuse” (Line 5, 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 drug takers
[C] alcohol and tobacco are as fatal as heroin and cocaine
[D] many substances other than heroin or cocaine can also be poisonous
52. The word “pervasive” (Line 1, Paragraph 2) might mean.
[A] widespread
[B] overwhelming
[C] piercing
[D] fashionable
53. 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
54. 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
答案：DAAB
