生态城市

生 = 牛 + 一 : Mnemonic symbol: a cradle.

Sherlock Holmes (sh) comforts a crying baby bull (牛) in a cradle (生) in front of the engine ((e)ng1) and plays him a tune on a flute (一).

态 = 太 + 心 : The empress dowager (太) asks Tecumseh (t) about his attitude (态) towards her in the airplane's bathroom (ai4). Tecumseh isn't sure himself and samples his hearts (心) on a scale from 1 to 10 with one bin per integer. After N is large enough, he sees that his attitude forms a Gaussian distribution (态) with a mean of 6.

城 = 土 + 成 : Again Charlie Chaplin is unable to exit engine. There is a wall of dirt blocking the entrance, and a progress bar showing that it will be removed soon, but the bar seems to be stuck.

市 = 亠 + 巾 : Mnemonic symbol: a supermarket.

Sherlock Holmes (sh) started a supermarket (市) in the space station's bathroom (Ø4), but all he has for sale right now are berets (亠) and towels (巾). He should have opened it at the beach!