placebo group的用法和样例：
例句
- Aderse eents did not differ significantly between the risedronate and placebo groups, the inestigators say.
研究人员说，治疗组和安慰剂组的不良反应发生率无显著差异。 - Although myalgia and pyrexia were more common in treatment groups, dropout rates related to treatment were similar to those in the placebo group.
尽管治疗组中，肌痛与发热更为常见，但由于治疗反应而推出的比例，与安慰剂组类似。
