① effective意為“有效的,效果好的”,指能產(chǎn)生具體的效果或預(yù)期的效果。還可表示“給人以深刻印象的”,可用于人或物。
The medicine is effective against cancer. 這藥有抗癌效力。
It is an effective sales program. 這是一個有效的銷售計劃。
The audience was moved by her effective speech. 聽眾被她動聽的講演所感動。
He is an effective assistant to Professor Wood. 他是伍德教授的得力助手。
② effectual意為“有效的,能奏效的”,正式用語,常同否定詞連用,指物不指人,被修飾的通常為行為、步驟、措施、藥物等。
This drug is effectual only in some cases. 這種藥只是對某些疾病有效。
There was no effectual measure against water pollution at that time. 當時沒有有效措施防治水污染。
③ efficient意為“效率高的,能勝任的,得力的”,可指人或物。
She is very efficient in reducing waste. 她在減少浪費方面卓有成效。
It is a highly efficient diesel engine. 這是一種效率很高的柴油機。
The manager is both competent and efficient. 這位經(jīng)理精明能干,辦事效率又高。