had been grading

• 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 grade.
  grade

  noun

  a degree or step in a scale, as of rank, advancement, quality, value, or intensity.

Related Words

• category
• class
• classification
• condition
• degree
• level
• quality
• size
• standard