工於心計

工 = 二 + 丨 : Mnemonic symbol: a steel beam, since 工 looks like the cross section of a steel beam.

Gitta Giraffe (gu) is working a shift in front of the engine ((e)ng1). Her job is to melt dinosaur bones (丨) so that they can be disposed off easily. To melt the bones, she is shorting a huge capacitor (二) with a steel beam (工) which consequently heats up to a bright glow. Using the glowing hot steel beam she can melt the dinosaur bone easily.

于 = 亅 + 二 : Mnemonic symbol: prepositions (in, at, on, to, ...) are what glue the sentence together. Honey is as sticky as glue, so I'll represent 于 by a honey jar.

Yu the Great (于) was assigned to repair the electronics of the space station's kitchen (Ø2), but instead he was snacking honey from a honey jar (于). Unfortunately his capacitor (二) got stuck in the honey and now he has to use a crowbar (亅) to lever it out.

心 = 乚 + 丶 : Marie Curie (xi) uses a shovel (乚) to dig a hole in front of the encampment ((e)n1). She wants to bury her heart (心). To the side are three petal leaves (丶), with which she wants to cover it afterwards.

计 = 十 + 讠 : Joan of Arc inspects an advertising column in the space station's bathroom. On it there is an intricate pattern of crosses. With an calculator she tries to calculate the overall area the crosses take on the advertising column.

计 = 十 + 讠 : Joan of Arc inspects an advertising column in the space station's bathroom. On it there is an intricate pattern of crosses. With an calculator she tries to calculate the overall area the crosses take on the advertising column.