To Have Been Doing

What Is "To Have Been Doing"?

"To have been doing" is known as the perfect continuous infinitive. It combines aspects of the perfect tense (completed action) and the continuous aspect (ongoing action), but refers to an action that was ongoing before another point in time—often in the past.

This form is used after certain verbs (like seem, appear, must, can’t) or in passive constructions to express duration leading up to a past moment.

Structure

to + have + been + present participle (-ing form)

Common Uses & Examples

• Expressing duration before a past event:
  She seems to have been working here since morning.
• With modal verbs for logical deduction:
  He must to have been sleeping—he didn’t hear the doorbell.

  Note: Correct form is "He must have been sleeping..." — the "to" is dropped after modals.

• In passive voice constructions:
  The project is believed to have been developing for years.
• Showing cause of a present result:
  You look tired—you appear to have been running!

Tips for Learners

1. Don’t confuse it with the present perfect continuous ("has been doing"). The infinitive form lacks a subject and often follows other verbs.
2. After modal verbs (must, might, could), drop the "to": "She must have been crying."
3. Use this form when you want to emphasize both the duration and the completion before another time.

Practice Yourself!

Try rewriting these sentences using the perfect continuous infinitive:

• "It looks like they were arguing for hours." → They seem to have been arguing for hours.
• "Maybe she was practicing piano all afternoon." → She might have been practicing piano all afternoon.