刻苦努力

刻 = 亥 + 刂 : Mnemonic symbol: an engraver.

The boar cannot believe it when it meets Karl Marx in the elevator's bathroom! Bewildered it asks for an autograph but has nothing except for a kitchen knife and an engraver. It takes Karl Marx a quarter of an hour to engrave his message in the kitchen knife: "Dear boar, keep on fighting capitalism! Yours, Karl."

苦 = 艹 + 古 : Karl Koala decided to repent for his sins and retreated into a cloister inside the space station. There he leads a very simple life full of hardship, e.g. he gave up on eucalyptus and just eats very bitter artificial lawn.

努 = 力 + 奴 : There is an emergency in the space station (Ø3), but both Nelson Newt (nu) and the slave (奴) are too weak to push the emergency power button (力). They exert (努) all their power to push the button together and let ground control know of the emergency.

力 = ㇆ + 丿 : Mnemonic symbol: a power button.

Li Qingzhao (li) just had a shower in the space station's bathroom (Ø4) and wants to use the hair dryer, but there's no plug, just the bare end of the cable! She uses all her power to build an electricity plug, and for the two pins she uses a plough (㇆) and a banana (丿). Finally she hits a big power button (力) to turn the power on.