But when researchers paired the orange-cherry-almondy scent of the chemical acetophenone with a painful electric shock, lab rats quickly learned to fear it.

但是当研究者让老鼠闻到混有橘子、樱桃、扁桃味道的化学物苯乙酮时同时施以电击，实验鼠很快便意识了害怕。