Stepping
来自Big Physics
Old English stæpe, stepe (noun), stæppan, steppan (verb), of Germanic origin; related to Dutch steppen and German stapfen .
wiktionary
From Middle English steppyng; equivalent to step + -ing.
etymonline
stepping (n.)
early 14c., verbal noun from step (v.). Stepping stone first recorded early 14c.; in the figurative sense 1650s.