圓錐曲線

圆 = 员 + 囗 : Yu the Great (yu) is having dinner in the anthill's kitchen (an2). There is a waiter (员) serving her food from a wooden box (囗) until Yu the Great is as round (圆) as the full moon.

曲 = 囗 + 卄 : Mnemonic symbol: a harp. Cupid (qu) is playing a harp (曲) in the space station's living room (Ø3). He's sitting on a big enclosure (囗), playing the harp (曲) and wielding a double axe (卄) at the same time.

线 = 戋 + 纟 : Mnemonic symbol: barbed wire.

线 = 戋 + 纟 : The silk worm wants to use the floating tank in the anthill's bathroom, but there's already Marie Curie inside—and she secured the tank by setting up barbed wire all around it.