六级练习2012.06.21 only, dangerous, chemical, approved, only, dangerous, chemical, approved

Rebecca949

In order for a chemical to be considered a drug, it must have the capacity to affect how the body works. (1)_________________________. Drugs are approved only after tests have demonstrated that they are relatively safe when used as directed and when their benefits outweigh their risks.
Thus some very dangerous drugs are approved because (2)______________________. Many people suffer ill effects from drugs called side effects, (3)________________________. The human population contains a great variety of genetic variation, but drugs are tested on just a few thousand people.

本帖隐藏的内容需要回复才可以浏览

lkl123

daan

susan.sui

1.** have the power to do this. it's completely safe.
2. they are necessary to treat serious *.
3.even though they take the drug exactly as directed.