Translation:I use the subway.
The "underground" in British English (in a transport context) refers specifically to the London Underground Railway System, as far as I'm aware. Subway is still used in British English- but is usually in reference to a path under something else (a road) etc. In other usage, subway is still generally understood as a shortening of "subway train". So, if we assume we're describing a foreign (Japanese...) underground train, subway seems perfectly appropriate.
Honestly, to use take in this instance is like....a lingual colloquialism. To take as a standalone verb means to remove. To ride (norimasu) or to use (tsukaimasu) both have different connotations as well, but are both usable in this case.
It's honestly better to identify that take isn't the 'correct' word, even though it's used. It could cause confusion later down the road when you associate, say, tsukaimasu with "take" and then have a minor mental shock when they use it with toilet or something.
に is a time/location particle, so it's usually only used for phrases such as "in" or "at." Using に here wouldn't make much sense, as ちかてつ is not the location/time in this sentence. For example: it WOULD be in the sentence: ちかてつにのりました。(I got off the subway.) But, in this sentence, ちかてつ is the direct object, so we would use the direct object particle (を).
Yes, you are right that に can be a time marker, but it can also mean "in" or indicate direction "to." You absolutely must use it with のります。It doesn't make any sense to use を, as that would somehow give the nuance of "through."（はしをあるきます＝I walk over the bridge, as opposed to just "on" the bridge.)
There are other times when it will be interchangeable with へwhen it indicates direction (がっこうにいきます・がっこうへいきます。), but not here.
For now, just memorize what particles go with what verbs. It will become second-nature to you eventually.
「のる」 is the "dictionary form" or "plain form." This is how it looks in the dictionary, and you can also use it when you are talking to your friends (but not your boss or your teacher, for example.). 「のります」 is the 「～ますform」, also known as the polite form. You can also turn a verb into a noun often by chopping off the ますpart.
Nevermemory, it's been a while, but do you remember the context in which you saw「のり」? I had just assumed the ます was at the end.
To go from dictionary form to ますform is super easy. First of all, you have to decide if your verb is a one-step verb (also called る-verb, but I don't want to confuse you because のる ends with る...) or a five-step verb. Five step verbs go through five steps (あ・い・う・え・お) to get every single inflection you could possibly want. For the ます-form, just take that last syllable and make it rhyme with い, then add ～ます。 So 「のる」 becomes 「のります。」
(one-step verbs: Just chop off the る and add -ます。So 「たべる 」becomes 「たべます。」）
To get back to your question, nicolajade95, as a teacher, the nuance totally wouldn't bother me. I wouldn't mark anyone wrong for using one over the other. But sometimes Duolingo is super picky, and wants a strict literal translation. If you feel the nuance between "use a subway" and "ride a subway" shouldn't make a difference, then hit the "report" button when it tells you that you are wrong. Eventually, Duo will have all the variants.
Does that help? I got off on a tangent yet again. But I feel you can learn language faster if you look for the patterns. Recapping: I use the subway (つかいます） vs. I ride the subway (のります)
Thanks a lot for this in depth comment, it has helped so much! Yes, I think you were right when assuming のります came as a pair, but I'll keep an eye out now just in case.
Is there a rule to know which verbs are one step and which are five, or will this be something I'll just have to learn by exposure? Nevertheless, I'll be able to look out for it now and actually understand what's happening. Thanks again MadameSensei :)
Dear Deka Dally is right to look for the verbs that have an ～える or ～いる sound, such as ねる・たべる・おきる。。。
Be careful, though, because there are a small handful of 5-step verbs that sound like ～える・～いる （かえる・はいる）。
Just because I am feeling particularly geeky today, I'll explain where the "five steps" comes from. Let's take つかう for example.
We're going to inflect it along the あ・い・う・え・お line. That is, the last syllable is going to change. (I apologize for Duolingo formatting. It makes more sense when they all line up in a column and you can see the あ・い・う・え・お
つかわない I don't use/he doesn't use/etc.、but in plain form. (Perhaps this is a poor choice to start with: It should be つか-あ-ない, but that would sound weird, so the "w" sound gets snuck in. We'll save that explanation for a later time.)
つかいます I use/he uses / (This also gives you the～ません・～ませんでした・～ましょう forms)
つかう I use/he uses (plain form AKA dictionary form)
つかえる・つかえます I am able to use/ he is able to use (～ません will give you "I am not able to use," etc.)
つかおう "Let's use..." (plain form)
Let’s try のる. It's going to inflect on ら・り・る・れ・ろ. So that last syllable will change.
のらない I don't ride (informal, AKA plain form)
のります I ride
のる I ride (dictionary form AKA plain form)
のれる I am able to ride
のろう Let's ride! (plain form)
Once you know one verb, you know all the verbs. There are only two irregular verbs, and even they work similar to this. The る verbs will just take off the る and slap the endings on. Japanese is so logical!
To answer your question, only sometimes. I'll do my best to answer this:
When going from ます-form to plain, there is no way to tell because every verb ends in the い or え sound, and therefore you cannot know whether they are る-verbs or う-verbs (MadameSensei called these "five-step verbs").
When going from plain to ます-form, however, you can tell because any word that doesn't end with the いる or えるsounds is a う(five step) verb.
Yes, exactly as you wrote it: 使う
Five-step verbs are so-called because the last syllable will move through all five vowel sounds. (On the う-line, moving to あ would sound weird, so it's going to turn into わ.)
使わない "I don't use..."
使います （使いません・使いましょう・etc.) All the ~ます forms
使う Dictionary Form or Plain Form
使える・使えます "I am able to use..." (or "He is able to use" or "They are able to use," etc.)
使おう "Let's use..."
One-step verbs are the verbs that end in an ～える or ～いる sound (with a small handful of exceptions.) Just lop off the ending and add your new ending. (Hence "one step.")
Japanese is so logical! Even the two irregular verbs work the same as all the other verbs.
So hopefully, given any verb, you can now figure out the dictionary form.
Very interesting question! Car, subway plane, foot are all countable nouns so why when using 'by' does the article get a 'bye'? These are zero articles and there are a few other circumstances (Eg A change of ...., switch from ....etc) where articles are dropped. Some suggest it avoids the confusion of specificity of the noun but then how do you explain "At night" vs "In the afternoon/morning/evening" or "in the home" vs "at home"?
を is the direct object marker. You have no choice but to use it in this phrase. で wouldn't work here; に would be ungrammatical; は would be emphasis that there is a negative coming up and you DON'T use the subway, も would work if you are saying, "I use the bus (or a bike or a car or walk...) and also the subway."
But this sentence can also mean "I will take the subway." If you want to say "currently," you'll use the て-form of the verb : つかっています, or even a different verb might sound more natural: のっています。
Hope this helps!