216Paragraph 2__________ 查看材料A.Are clinical trials saf9047

Paragraph 2__________ 查看材料 A.Are clinical trials safe？ B.What are clinical trials？ C.What should people know before participating in a clinical trial？ D.Who should consider clinical trials and why？ E.Where are clinical trials conducted？ F.Why are clinical trials done？ 请帮忙给出正确答案和分析，谢谢！