0

This exercise is from Raymond Murphy's English Grammar in Use. The exercise is to practise using "could have done" and "couldn't have done" (not "could do"!).

Read this information about Ken:

Ken didn't do anything on Saturday evening. Ken doesn't know anything about machines. Ken was free on Monday afternoon. Ken was short of money last week. Ken's car was stolen on Monday. Ken had to work on Friday evening.

Some people wanted Ken to do different things last week but they couldn't contact him. So he didn't do any of these things. You have to say whether he could have done or couldn't have done them.

  1. Ken's aunt wanted him to drive her to the airport on Tuesday. Answer: He couldn't have driven her to the airport (because his car had been stolen).

The idea is that it would not have been possible for Ken to drive his aunt to the airport, even if she had been able to contact him. "Could do" is not correct. But if we change the context and don't use it in the sense of "it would not have been possible for him to do that" and instead say "Ken's aunt wanted/asked him to drive her to the airport on Tuesday, but he couldn't (drive her ...)", then doesn't that make sense? Is it correct?

Improve this question

1 Answer 1

Reset to default
1

If I understand your question correrctly, you are asking about the difference between these sentences:

  1. He couldn't have driven her to the airport (because his car had been stolen).

  2. He couldn't drive her to the airport (because his car had been stolen).

Both are grammatically correct, making use of "could" (a modal verb in preterite form) to describe a past event.

The first sentence also uses the perfect aspect, which implies an earlier time. That would be appropriate if the "wanting" happened after the possible "driving". For example:

On Thursday Ken's aunt wished that he had driven her to the airport on Tuesday, but he couldn't have done so because his car had been stolen.

Otherwise, the perfect aspect is unnecessary:

On Tuesday Ken's aunt wanted him to drive her to the airport, but he couldn't do so because his car had been stolen.

Improve this answer
7
  • thank you. I meant would it be wrong to use "could" instead of "could have done" in this sentence : He couldn't have driven her to the airport (because his car had been stolen), to mean "it would not have been possible" for him to do that, because "could" "not" doesn't mean that? But as a standalone sentence if I say "he couldn't drive her because his car had been stolen" it is correct, isn't it? I mean "could not" can't mean and can't be used instead of "could not have driven" or "would not have been able to drive."
    – Antonia A
    Commented Feb 6, 2022 at 6:47
  • 1
    I'm still not exactly sure about what you're asking, but I think that I answered it. Yes, it is possible to "use "could" instead of "could have done" in this sentence". That is the last example in my answer (". . . he couldn't do so . . ."). As I said in my answer, the meaning is a bit different if you use the perfect aspect, so you can use it as long as it has the meaning that you intend.
    – MarcInManhattan
    Commented Feb 6, 2022 at 21:00
  • sorry if my question wasn't clear. I meant to say that using "could not" instead of "could not have done" isn't correct because they have different meanings. If the intended meaning is "he wouldn't have been able to drive her" I should use "could not have driven her" not "could not drive her". But if I want to they he didn't manage to drive her I can say "he couldn't drive her". Is it correct?
    – Antonia A
    Commented Feb 7, 2022 at 7:28
  • 1
    Yes, that's correct. Tenses with modals are very tricky because both present and preterite forms can be used to describe past, present, or even future actions. And things get tricker, of course, with the perfect aspect. Therefore, the "rules" aren't as clear as for other verbs, and you'll find quite a bit of variability among native speakers. I think that you have the basic idea, though.
    – MarcInManhattan
    Commented Feb 7, 2022 at 9:41
  • 1
    Yes, the modal verb "could" already contains the meaning of "to be able", so "he could not have driven her" basically means the same thing as "he could not have been able to drive her". (There is a difference, but it's somewhat subtle.) However, we're getting into other issues here, so perhaps you should ask a new question! :)
    – MarcInManhattan
    Commented Feb 7, 2022 at 10:05

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .