ADVANCED VERB FORMS EXERCISE 3: SHOULD/COULD/MIGHT HAVE (ESL)

Grammar review Should have / could have / might have + past participle

All three look alike on the surface (modal + have + past participle), but each one makes a different claim about the past. Getting the choice wrong doesn't just sound slightly off; it changes what actually happened.

Should have + past participle: regret or criticism
Says an action didn't happen, but it was the right or expected thing to do.
“You should have worn a coat.” (you didn't wear one, and you should have)
“I shouldn't have eaten so much cake.” (I did eat it, and I shouldn't have)

Could have + past participle: a missed possibility
Says someone had the ability or opportunity to do something, but didn't use it.
“He could have finished the race, but he gave up.”
Negative form is different: couldn't have means impossible, not "didn't but could have": “It couldn't have been my sister. She was at work all day.”

Might have + past participle: uncertain speculation
Says something is a possible explanation, but you're not sure.
“The noise might have been the neighbors.” (one guess among several; we don't know)

Quick test: Ask yourself what you're actually saying. Judging what someone ought to have done → should have. Pointing out an option that went unused → could have. Guessing at an explanation you can't confirm → might have.

This is the third and final exercise in the Advanced Verb Forms series. See also Exercise 1: Past Perfect in Reported Thought and Exercise 2: Never Would Have....