"I eat an apple."
Translation:Saya makan apel.
The stated "correct" answer is only one of many possible answers it will accept if you're typing in.
I presume this issue is more of an issue you've run into while using the "picking words" mode?
In any case, me- verbs are introduced more properly in a later level. I believe the same goes for the single-quantity se- words like sebuah (literally "a fruit of")
I was already learning Indonesian beforehand, but I hadn't heard of some of these more "formal" versions of the words For an improvement, I'd introduce the words (and the meanings of the prefixes and suffixes that make them up) beforehand to avoid confusion I really like the learning style Duolingo uses compared to some other programs I've used, and I understand that it's a beta, but introductions to avoid confusion would really help!
What level of the "basics" questions did you first encounter this particular version of the question at? For me, I only noticed it at level 5; perhaps the assumption is that you're supposed to have progressed further in the course to the point that these other concepts have already been learnt, before you come back to upgrade "basics" to the higher levels?
I got this as a drag-and-drop sentence and chose "Saya makan sebuah apel", which is accepted as correct, but it tells me that another correct solution is with "memakan" instead of "makan", but "memakan" is not an option in this drag-and-drop exercise. I find it frustrating that it shows me another correct solution when that solution is not a possible solution with the words given to me.