New words：

ineffective [ini'fektiv] adj. 无效的；不起作用的；不奏效的
effectiveness [i'fektivnis] n. 效果；有效性；效能；效力；效率；成效
ineffectiveness [.inə'fektivnis] n. 无效；低效率；无能力

Sample Sentences：

An ineffective person should not be our leader.
The air-conditioner was ineffective in such a crowded room.
Scientists have carried out experiments to test the effectiveness of the new drug.

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