Why is it not कमरा (kamra)? Shouldn't कमरे mean plural, she is in the rooms?
How can we guess that it ought to be she is in the room ? Where in the Hindi sentence points out the usage of the in English translation?
Are you asking about the word 'she'? "He is in the room" would also be a valid translation and should be accepted.
Oh no I mean why can not we omit the in the English translation. I mean is she's in room can also be a valid translation? Thanks for your concern on my previous doubt. And for your idea, I'm not able to find notifications in duo website. I'm getting the notifications from my mail and thus the late reply.
English has both indefinite articles (eg: a, an) and a definite article (the) and one or the other is used to specify definiteness of a common noun (so, 'she's in room' won't be grammatically correct). In contrast, Hindi does not have a definite article and so, absence of an article indicates definiteness by default. The word for 'one', एक serves as an indefinite article. Therefore, वह कमरे में है। would be "He/She/It is in the room" and वह एक कमरे में है। would be "He/She/It is in a room".
Unfortunately, I don't think Duo has website notifications.