Hello Ana and welcome to the Greek course! Please read the tips and notes for the Basics skill here https://www.duolingo.com/skill/el/Basics-1/tips-and-notes, everything is explained. Check the Greek forums here https://forum.duolingo.com/topic/936 for more resources on the keyboard, grammar and much more.
Both are correct you'll find many words in Greek with different ways of spelling. It's best and easiest to get used to using one but recognizing the other. On Duo whichever you use will be correct for most exercises except for the Listening where you must write what is said.
Have a look at these tips for further help
TIPS TO MAKE LEARNING EASIER + HOW TO REPORT A PROBLEM
Ok, let's see what is going on. Did you read the comment above yours? It says:
- "On Duo whichever you use will be correct for most exercises ...
So, that answers your question....both "άνδρας" and "άντρας" on most exercises. What kind of exercise was yours? You should have told us.
- except for the Listening where you must write what is said.
So, was it a listening exercise? Well, there is your answer because the listening say..."άντρας" οnly.
If it wasn't a Listening exercise perhaps there was a problem with the rest of the sentence.
Please use the tips shown in the comment above.
TIPS TO MAKE LEARNING EASIER + HOW TO REPORT A PROBLEM from now on.
What kind of exercise was it? Because if it was a Listening exercise then only
I put "άνδρας" instead of "άντρας" but it was rejected,
But the sentence did not consist of only one word, did it?