English grammar

Past Modals

"I must have lost it" (a guess about the past). "She could have called" (she could, but she didn't). "They might have already left" (maybe they left). "It shouldn't have been done" (that was wrong). In real talk, people say "should've", "could've", "must've". This sounds like "of". Some people write "should of" by mistake. Past modals are hard to learn. But people use them a lot when they talk.