馬來(lái)西亞dba博士免聯(lián)考

考研英語(yǔ)閱讀出題點(diǎn)：因果關(guān)系處

【試題回放1997-Text3】

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.

61. Physical dependence on certain substances results from ________.

[A] uncontrolled consumption of them over long periods of time