不定式

不 = 丆 + 卜 : Bruno Bear (bu) is setting up a wind wheel (丆) with a voodoo staff (卜) in the space station's bathroom (Ø4). He also puts a "forbidden" sign (mnemonic symbol for 不) on it, to make clear that it may not (不) be stopped.

定 = 宀 + 下 + 人 : "to fix": duct tape. Somebody wanted to tease Dorothy Gale and taped a graduation cap to her head. Neanderthal Man tries to help her by levering the cap off with a ladder in the engine's bathroom.

式 = 工 + 弋 : I'll use a specific style as mnemonic symbol: 哥特式, gothic.

Sherlock Holmes and the goth are celebrating a Viking festival in the space station's bathroom. They don't have trunks to throw around, so they use a steel beam. They also celebrate by practising archery. In zero gravity it is easy for them to set one world record after the next.