永久性

永 = 丶 + 水 : Yu the Great just got the most romantic proposal ever! In engine, somebody prepared a water fountain and had a diamond ring floating on a petal leaf float over to her. Unfortunately Yu the Great doesn't know who the ring is from, as her lover drowned in the water fountain earlier that day.

永 = 丶 + 水 : Mnemonic symbol: as the advertisements tell us, diamonds are forever. I'll represent 永 with a diamond ring.

久 = ㇏ + 勹 : Mnemonic symbol: an hourglass.

Joan of Arc (ji) has been waiting for ages (久) for the elephant (勹) to get up from the outhouse's living room (ou3) sofa. She point towards a huge expired hourglass (久) and pokes him with a finger (㇏) to make him finally get up.

性 = 忄 + 生 : Marie Curie had a strong character since she was little. Even in her cradle in the engine's bathroom she was only playing with a flail.