Caught my gf kissing our lab sir

OK now that I've tricked u, can anyone tell me if I have to write answers in board as per ncert language, our can I frame my own as per my own wording. I have Xam idea for science and lot of the toppers answers are in their own words, not ncert.

My teachers tell me to write answers using ncert language, so do I to mug up everything? Or can I frame what is correct as per My own wording