1、Despite their best efforts, the treatment proved to be inefficacious in curing the patient's disease.
尽管他们尽了最大的努力，但这种治疗方法对治愈患者的疾病无效。
2、The company decided to withdraw the inefficacious product from the market due to numerous complaints from customers.
由于顾客的众多投诉，该公司决定将无效的产品从市场上撤下。