不入虎穴，焉得虎子 [ bù rù hǔ xué , yān dé hǔ zǐ ]: How do you catch the tiger cub without entering the tiger's lair? (idiom); Nothing ventured, nothing gained.

割鸡焉用牛刀 [ gē jī yān yòng niú dāo ]: lit. why use a pole-ax to slaughter a chicken? (idiom); fig. to waste effort on a trifling matter; also written 杀鸡焉用牛刀

塞翁失马焉知非福 [ sài wēng shī mǎ yān zhī fēi fú ]: the old man lost his mare, but it all turned out for the best (idiom); fig. a blessing in disguise; it's an ill wind that blows nobody any good

心不在焉 [ xīn bù zài yān ]: absent-minded; preoccupied; inattentive; with one's thoughts wandering

于焉 [ yú yān ]: (classical) see 于是