In each of the following pairs of phrases, what is the difference between the two?

1a. "Had been able" vs.
1b. "Could have"

2a. "Hadn't been able" vs.
2b. "Couldn't have"

  • You may well find our sister site English language Learners more helpful on this.
    – WS2
    Commented Oct 28, 2015 at 21:53
  • 2
    Is your question about verb forms -- had been (past perfect) vs have been (present perfect) or about semantics -- the meaning of "hadn't been able" vs "couldn't have been able" or both? It would be helpful to see complete illustrative sentences that you're having trouble distinguishing between.
    – deadrat
    Commented Oct 29, 2015 at 0:53

1 Answer 1


In each pair, the first phrase is about having accomplished (or not) something in the past:

Before arthritis got to his back, he had been able to change his own oil

Before he got his GED, he hadn't been able to get anything better than work as a laborer

The second phrase in each pair is about opportunity, most typically that was missed:

He could have gotten her autograph if he'd had the courage to walk up and say "hi".

He couldn't have eaten the last piece of cake, he was away at school all day.

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