ineffective

adj.无效的,(指人)工作效率低的

无效的；不起作用的；不奏效的

形容词

1、The treatment proved to be ineffective in curing the disease.
治疗方法证明对治愈疾病无效。
2、His attempt to persuade her was ineffective; she remained unmoved.
他试图说服她，但无效；她仍然不为所动。