lest
conj. 以免，避免；唯恐，担心
例句
He gripped his brother's arm lest he be trampled by the mob.
他紧抓着他兄弟的胳膊，怕他让暴民踩着。
《牛津词典》
Prithee master thy tongue, lest we be all beaten till we die!
请你管好你的舌头，免得我们都挨打，直到死！
Boil the oil soiled by the coil in the toilet lest it spoils.
把被盥洗室里的线圈弄脏的油煮开，以免变质。
