had been double-checking

• 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 double-check.
  double check

  noun

  a simultaneous check by two pieces in which the moving of one piece to give check also results in discovering a check by another piece.

Related Words

• affirm
• approve
• back
• certify
• corroborate
• endorse
• establish
• explain
• sign
• substantiate
• support
• uphold
• verify