Could not have past participle Hi, I read this article:https://www.perfect-english-grammar.com/could-have-should-have-would-have.html 2: We use could have + past participle when we want to make a guess about something that happened in the past. (See also modals of probability.) In this case, we don't know if what we're saying is true or not true. We're just talking about our opinion of what maybe happened. Why is John late? He could have got stuck in traffic. He could have forgotten that we were meeting today. He could have overslept. And here is my question: can I use could not have p.p as an assumption in the past as above? For example, can I say “he couldn’t have passed the exam because he is crying. (= I think he didn’t pass the exam because he is crying.)”? Does it make sense? Thanks.