it's Q9 incorrect, just reporting it
On the contrary, it's correct: 'why we don't' is an indirect question because of 'I wonder' at the beginning.
I agree with you but what is the verb here? I cannot see the base form of the verb. Should it be "take"?
Q9 - I was wondering why ____ the train; it'll be quicker.
Would it be more correct to say: I was wondering why we didn`t take the train [?]
Oops- sorry, I was looking at the answer... Thanks- will change it now. ;-)
We often use 'I was wondering' when introducing a present doubt, query, etc; it sounds more tentative. ;-)