Concerning the answer of the following question, could I add my point of view?
-........until the car had been checked before you returned home?
a) Did you wait
b) Had you waited
🔵I appreciate your efforts.I respect the site greatly.I think it is not natural to start a part of conservation with past perfect.I know that past perfect makes a connotation between the clauses, but I think
🔵."Did you wait.." is OK here
The speaker is inquiring, starting a conversation.
🔴Past perfect is when we focus on the sequence, moreover it would be confusing if we chose past perfect as we wouldn't know which one of them started first, 'checking or waiting.'This my humble point of view.