had been machining

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of machine.
  machine

  noun

  an apparatus consisting of interrelated parts with separate functions, used in the performance of some kind of work.

Related Words

• apparatus
• appliance
• automobile
• engine
• gadget
• instrument
• motor
• tool
• vehicle