In russian there is two different meanings:
Они в метро - they are located below ground, IN the subway station or train. We can used it when want to say, that you can't call them with mobile, because there no signal IN subway.
Они на метро - they are moving WITH USING subway (metro train), and now they are moving on train or move anywhere through the station. We can use it when want to say, than you can't see them on the usual bus stop, because they moving WITH undeground.
Excuse me, but in English [US], we would most commonly say, "Are they at the subway/metro?" Due to the metro being a place to be, and not necessarily the metro "train" itself. Unless they are speaking about that, in which case, please do disregard this comment, as that would make sense. :)
No native speaker ever says, "I am at the subway/They are at the subway." We say, I am on the subway/They are on the subway." In some rare cases, we may specify, "I'm in the subway.", but likely only in a case such as, "OK I'm going to lose cell service, I'm in the subway now."
Little problem ive been encountering with this app when learning Russian when i put it how it is read in Russian its wrong for example intead of it being where is guitar it says its where is a guitar from what many of my Russian friends have told me it shouldn't have an a in it seeing in russia it would translate over to where is guitar
It also implies that Russia goes by the English grammar system there for it is incorrect.
I also translate Russian everyday and ive never seen anyone a in a sentence before and the only reason i have this app is to get a better grasp on the alphabet when it comes to the unfimilars as some call them
Sorry for ranting on so long its just im very frustrated about this and it keeps wasting my life's and slowing me down. Im hoping that they will make both correct answers.