I shouldn’t have done that
I should have done that means I didn’t and now I feel bad about it.
I shouldn’t have means I did it and now I feel bad about it.
I wish I could go back and change what I did then.
I wish/if only
I Wish and “If Only” are other ways to express regrets and wishes that the situation were different.
Ifs and wishes take a step back in the verb tense
I wish I had called…. means I didn’t
Use past perfect form to mean simple past time
*Do not use “was” with ifs and wishes. Always use “were”
I wish he were here.. means he isn’t
Use simple past form with simple present time
- https://www.ecenglish.com/learnenglish/lessons/should-have-past-participle (Links to an external site.)
- https://www.examenglish.com/grammar/B1_should_have.htm (Links to an external site.)
Should (present/future) vs. Should HAVE (past/regret)
- http://speakspeak.com/english-grammar-exercises/intermediate/should-vs-should-have (Links to an external site.)
- https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-16638.php (Links to an external site.)
Wishes take a step back
- http://www.myenglishpages.com/site_php_files/grammar-exercise-if-only-I-wish.php (Links to an external site.)
- https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-84051.php (Links to an external site.)
- https://www.test-english.com/grammar-points/b1-b2/wishes-regrets/ (Links to an external site.)