听力原文：Technically, any substance other than food that alters our bodily or mental funct

听力原文： 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 drngs. This is why the neutral term "substance" is now used by many physicians trod psychologists. The phrase "substance abuse" is often used instead of "drng 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 substance 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 Obviously constructive uses of a substance become misuses？ First of all, most substances taken in excess will produce side-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 eftect, and then by the appearance of unpleasant withdrawal symptoms when the substance is discontinued.

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A．Drug.

B．Substance.

C．Medicine.

D．Alcohol.