工薪階層

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.

薪 = 艹 + 新 : Marie Curie (xi) received her salary (薪) in front of the encampment ((e)n1) which consists of a set of completely new (新) sheets of artificial lawn (艹). Unfortunately they catch fire and prove to be the ideal fuel (薪) for a quickly burning fire: the artificial lawn is burning down within seconds.

阶 = 介 + 阝 : The pope (阝) sentenced Joan of Arc (ji) to death and wants to shoot her to outer space using a rocket (介) in front of the elevator (e1). He doesn't have a proper launch ramp, so he just uses some stone stairs (阶).

层 = 云 + 尸 : The King of Chu (c) is enjoying a lasagna (千层面) in the engine's kitchen ((e)ng2) when suddenly a ghost (尸) surrounded by a dark cloud (云) appears and starts to haunt him. Terrified, the King of Chu drops the lasagna and runs away. The ghost reached its goal and starts devouring the lasagna himself.