六级练习2015.03.15
[audio]http://sound.yywz123.com/tingbbs/cet6/cet620150315.mp3[/audio]When a particular drug is taken by millions, some people may not respond in a predictable way, even though the drug has been tested.
A patient may also acquire a tolerance for a certain drug, which means the patient has to ______________________. Tolerance may lead to habituation, in which the person becomes so dependent on the drug that he or she becomes addicted to it. _________________________when the drug is taken away. Finally, drugs often have unwanted side effects. This usually causes only minor discomfort,____________________. Certain drugs, however, can produce serious adverse reactions.
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