"I am eating a third crepe."
Translation:Je mange une troisième crêpe.
I literally can't tell the difference between 'un' and 'une'. I know when a word has a 'e' in the end, I know the sentence would be, "Mes chemises sont vertes." However, I can't really tell which correct 'a' would make the sentence complete. I'm not sure if I'm alone in this but I really do need help. I've been really stumped since the first day I've been doing French in Duolingo. Help?
The gender really needs to be learnt along with the noun but they can be vaguely guessed at if you follow this guide:
Are you working through the tree slowly or are you trying to test-out? I'm guessing the latter as you only started studying on Duo on 9 April 2018 and you are already level 16. un and une is fairly basic knowledge and, if you were doing the exercises one by one, you would be able to learn from any mistakes. My advice is to slow down and absorb the language slowly.
Bon courage !