A challenge for me!!!

Wow! Piano theory grade 8 is really hard. Some more I have to finish it as soon as possible. Though I quite dislike my "piano teacher", but I still have to accept the fact that this teacher has taught me a lot of things. Thanks to her!
The problem is my theory knowledge is only up to grade 6. Wonder why I say grade 8 is hard? lol, as I can tell here is I'm actually skip grade 7 theory's learning.
And, this is the challenge for me: I need to refer many books and look for many examples.
Currently, I'm learning to fill up the trio sonata. Can anyone help me? Any tips to tackle this question? Hope I can get some ideas from all of you!!!