Can have done

[Rachel Adams]

Is it wrong to use "can" in these examples instead of "could," "may" and "might"?

1. "She could have warned me." To criticize someone.

2. "I am glad he didn't tell her the truth. It can have hurt her." To say that something was possible, but didn't happen.

My textbook "English Grammar in Context" by Michael Vince mentions only one use of "can't have done" when the speaker is sure that something isn't true. For example, "I still haven't heard from Peter. He can't have got my message."

For #2 it suggests using "might" or "could" not "may."

To criticize someone or something it suggests using "might" not "could" or "may".

To talk about something that could have happened but didn't happen it suggests "might" or "could" not "may."
I have learnt about other possible uses of different tenses, constructions, etc I was wondering if what the book doesn't mention is also possible.

 

[5jj]

1. "She could have warned me." To criticize someone.

2. "I am glad he didn't tell her the truth. It can have hurt her." To say that something was possible, but didn't happen.
.

You can use could or might in both. You can use can or may in neither.

 

[emsr2d2]

Is it wrong to use "can" in these examples instead of "could," "may" and "might"?

1. "She could have warned me." To criticize someone. Yes, it's wrong - you can't use "can" here.

2. "I am glad he didn't tell her the truth. It [STRIKE]can[/STRIKE] could/would/might have hurt her." To say that something was possible, but didn't happen. Yes, it's wrong - "can" doesn't work there.

My textbook "English Grammar in Context" by Michael Vince mentions only one use of "can't have done" when the speaker is sure that something isn't true. For example, "I still haven't heard from Peter. He can't have got my message."

For #2 it suggests using "might" or "could" not "may." I agree. I think the author is reserving the use of"may" for permission, not as an alternative to "might".

To criticize someone or something it suggests using "might" not "could" or "may". I disagree on this one. It's perfectly possible to say "She might have warned me!" in an exasperated tone, indicating that she did not warn you.

To talk about something that could have happened but didn't happen it suggests "might" or "could" not "may." Exactly. Sentence 1 is an example of something that could have happened but didn't and, as I said above, both "could" and "might" work.

See above.