The past perfect should be used in all of your sentences.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
CoincidenceI wonder whether the Past Simple could be used when the words 'just' and 'already' appear in a sentence.You can do that.
CoincidenceWe weren't hungry because we just had lunch.I'm sure I've heard something like this, but I'm not overjoyed by it. 'had had' is better, in my opinion.
CoincidenceWhen I got home my parents already went to sleep."when" is tricky. You'll need 'had already gone'.