So far, I've been using common sense to make out the rules for tenses.. but, perhaps there are some idiomatic usages I'm not aware of.
For example, in Ch. 33:
"Iulius dubitabat num magister Marcum laudavisset."
That's fine: "Julius doubted whether the teacher (had) praised Marcus," meaning, praised Marcus prior to Julius's doubt.
But, in the Pensum:
"Si industrius fuisset, te laudavit nec epistulam scripsit."
"If you had been busy (working), he would have praised you and would not have written the letter."
Is that correct?