工齡

工 = 二 + 丨 : Mnemonic symbol: a steel beam, since 工 looks like the cross section of a steel beam. In front of the engine ((e)ng1), Gitta Giraffe (gu) is doing some hard work: She's stacking a capacitor (二) on a dinosaur bone (丨) on a capacitor (二). She's not very successful, but then she gets the idea to use steel beams (工) as support.

龄 = 令 + 齿 : Li Qingzhao (li) wants to enter engine, but in the kitchen ((e)ng2) she has to undergo a check first. An old codger with an imperial name tag (令) is entitled to check her teeth (齿) in order to now Qingzhao's age (龄).