他在第三回合以一记左勾拳击倒对手获胜。

He won the match with a left hook ___knockout in the third round.

这场拳击比赛采用淘汰制，输一场就被淘汰。

The boxing match uses a ___knockout system, where one loss means you're out.

她穿着那件黑色礼服简直美得惊艳。

She was a total ___knockout in that black dress.

研究人员使用基因敲除果蝇来观察缺失基因的影响。

Researchers used a ___knockout fruit fly to observe the effects of a missing gene.