Third conditional is used to discuss things in the past that did not happen. These conditions can never happen because they refer to things that did NOT happen in the past. Sounds weird, but it's quite useful. It's basically saying, "What if something different had happened?" "PP" refers to past participle. The past participle of eat is eaten, send is sent, drink is drunk, etc. The PP is often the same as past tense (sent/sent, followed/followed, etc) but are different for irregular verbs (ate/eaten, drank/drunk, etc). The basic formula for 3rd conditional is: If + past perfect, would have + PP. It's important to note that past perfect is formed with: had + PP EXAMPLE: If I had studied, I would have passed the exam. The reality is that I didn't study so I didn't pass the exam. But if conditions had been different in the past (if I HAD studied), then the outcome (also in the past) would have been different.

Here is some good general information about the different types of conditionals. https://www.ef.com/ca/english-resources/english-grammar/conditional/ And some specific information about type 3 conditionals. https://www.ef.com/ca/english-resources/english-grammar/type-3-conditional/

Hello! We use the third conditional when we mention "impossible condition"(because something happened in the past). This is the way we imagine how things could have been different in the past. Notice that both the condition and the result are impossible now. E.g. "I would have gone too If I had known you were going to the cinema." Hope this helps :)