uselessness

She complained about the uselessness of the old printer.

用法提示：uselessness 是名词，表示“无用”的状态，在句中作介词 about 的宾语。

The uselessness of the argument became clear to everyone.

用法提示：uselessness 是名词，指“无益、无意义”的特性，在句中作主语。

He finally admitted the uselessness of trying to change her mind.

用法提示：uselessness 是名词，表示“徒劳、无效”，后接 of 加动名词结构。