to cross a river / to aid or relieve / to be of help
济
=
氵
+
齐
:
Joan of Arc (ji) accidentally knocked over the only water supply bottle (氵) In the space station's bathroom (Ø4) and now she's in big trouble. She uses the empty bottle as a drum to call for help (济), but it is of no use; she would need a gong instead. Unfortunately the drum is ready, but the gong is not (齐).