had been mainlining

• 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 mainline.
  mainline

  verb (used without object)

  to inject a narcotic, especially heroin, directly into a vein.

Related Words

• dominant
• key
• leading
• main
• major
• outstanding
• paramount
• predominant
• preeminent
• primary
• prime
• prominent