声
=
士
+
尸
+
丨
:
Sherlock Holmes (sh) hears the terrifying sound (声) of bone (丨) on stone in front of the engine ((e)ng1), and he's sure that there must be a ghost (尸). Indeed it's only the bachelor (士) who wants to scare Sherlock.
Mnemonic symbol: a balloon. The Queen of Hearts is disappointed by her balloons. She expected them to float upwards, but in the space station's bathroom, They float randomly in all directions.