这种药物作为多巴胺受体激动剂，用于治疗帕金森病。

This drug acts as a dopamine ___agonist to treat Parkinson's disease.

在做俯卧撑时，胸肌是主要收缩的肌肉。

The pectoral muscles are the ___agonists during a push-up.

两位文学界的角逐者为年度最佳作品奖展开激烈竞争。

The two literary ___protagonists competed fiercely for the annual best work award.