had been enhancing

• 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 enhance.
  enhance

  verb (used with object)

  to raise to a higher degree; intensify; magnify.

Related Words

• add to
• appreciate
• augment
• boost
• build up
• complement
• enlarge
• heighten
• increase
• intensify
• raise
• reinforce
• strengthen
• upgrade