l 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 “mindmanifesting”) because they seemed to radically alter one's state of consciousness.
“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
The word “pervasive” (Line 1, Paragraph 2) might mean _____.
A)widespread
B)overwhelming
C)piercing
D)fashionable
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
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
Passage 4
No company likes to be told it is contributing to the moral decline of a nation. “Is this what you intended to accomplish with your careers?” Senator Robert Dole asked Time Warner executives last week. “You have sold your souls, but must you corrupt our nation and threaten our children as well?” At Time Warner, however, such questions are simply the latest manifestation of the soul searching that has involved the company ever since the company was born in 1990. It's a selfexami
[责任编辑:bulesky]
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