[shu-] Sherlock Holmes is in the [4] bathroom of the [-(e)n] infirmary, which has a leak. A 顺 smooth 川 stream of water runs down from a hole in one of the pipes. Sherlock borrows a 页 page from a doctor nearby and pastes that over the hole, making the 顺 smooth 川 stream stop. All of the nurses think he is so 顺 smooth, and he simply says "elementary".