past tense - "Why couldn't" vs. "why couldn't you have"


Reading Harry Potter 2, I came across the following, and I wonder if the use of couldn't have is the equivalent of couldn't in this context?



"I have got a question, Oliver," said George, who had woken with a start. "Why couldn't you have told us all this yesterday when we were all awake?"



If we change it to the following, how does it change the meaning of it?



"I have got a question, Oliver," said George, who had woken with a start. "Why couldn't you tell us all this yesterday when we were all awake?"



And what is the difference between the following?



If you couldn't do it, you should have told us yesterday.


If you couldn't have done it, you should have told us yesterday.





Comments

Popular posts from this blog

verbs - "Baby is creeping" vs. "baby is crawling" in AmE

commas - Does this sentence have too many subjunctives?

time - English notation for hour, minutes and seconds

grammatical number - Use of lone apostrophe for plural?

etymology - Origin of "s--t eating grin"

etymology - Where does the phrase "doctored" originate?

word choice - Which is the correct spelling: “fairy” or “faerie”?