Tense selection

Question

My question regards choosing to translate using the imparfait or plus que parfait vs passé composé. Often I will choose the passé composé but the exercise will say  to use the imparfait or plus que parfait because of expressing an opinion. In this exercise, then, I used the imparfait instead of the phrase describing the first lesson: "....qui s'est très bien passée". Wouldn't this express an opinion? If not, then please help me to see the difference between this and "elle ne s'y attendait pas"

Answer

This idea that the imperfect is used to express opinions in the past is only so useful.

For example, 'he ate too much' and 'in my opinion, he ate too much' would both be '(à mon avis) il a trop mangé'.

I think what the rule is getting at is that the imperfect tends to be used for descriptions that are vaguer than hard facts, especially in terms of duration. But if the description sounds definite, with a clear start and end, there is no reason why it shouldn't be passé-composé (even if it's technically subjective or an opinion).