"I do not drink tea."
I like how Marco put it earlier, but it also helps me to think about like what the emphasis is. While both mean "I don't drink tea," the は emphasizes the tea as the subject - "I don't drink TEA (but I drink other drinks)/Tea is not drunk by me" versus with をit might be more like "I dont drink tea (but other people do)".
If you put を it's like "I wont drink the tea", for some reason you don't want to drink the tea now, but you may drink after. In this case, the tea is the object that you wont drink now for some reason. But when you say "I don't drink tea", you don't like tea or you can't, so probably you are not going to drink tomorrow neither after. So you use は because "Tea" is the topic that you don't drink.
は - referring to a topic. を - referring to an object.
Sorry for my english.
I'd be careful. While not exactly wrong, this isn't really the whole story and could easily lead to misunderstanding if you try to apply it to every sentence containing は or を.
This topic is discussed a lot in this thread, so I suggest reading the rest of the discussion and consulting other sources if you are still confused.
In Japanese, verbs can come in various forms, just like in English. Drink, drank, drinking .. all variations on the same verb.
Nomu is the most basic form of the verb "to drink". It is the non-past tense plain form, used in casual or non-formal speech or if you were looking up the verb in a dictionary (sometimes called the "dictionary form").
私は飲む (watashi wa nomu.) "As for me, (I) drink"
コーヒーを飲む (Kōhī o nomu) "(I) drink coffee"
Nomimasu is the polite or formal version of this basic form. It is also non-past tense and is used exactly the same, except that it is preferred in formal situations. You will see the formal endings quite frequently on DuoLingo and in other learning materials, since it is common to introduce new Japanese learners to formal forms very early.
私は飲みます (watashi wa nomimasu.) "As for me, (I) drink" (polite)
コーヒーを飲みます (Kōhī o nomimasu) "(I) drink coffee" (polite)
Nomimasen is the NEGATIVE version of "nomimasu". In Japanese, if you want to say that you do not do something, you conjugate the verb into its negative form. So if you want to say that you DO NOT drink, you would use the negative form of the verb "to drink". Nomu becomes "nomanai" and nomimasu becomes "nomimasen".
私は飲まない (watashi wa nomanai.) "As for me, (I) do not drink"
コーヒーを飲まない (Kōhī o nomanai) "(I) do not drink coffee"
私は飲みません (watashi wa nomimasen.) "As for me, (I) do not drink" (polite)
コーヒーを飲みません (Kōhī o nomimasen) "(I) do not drink coffee" (polite)
The example sentence above says "As for tea, (I) do not drink (it)"
おちゃはのみません。(ocha wa nomimasen)
Since the verb is in the negative, we know that the speaker is indicating that they do NOT drink something. Since "ocha" is the topic of the conversation, we can assume they are referring to tea.
So this sentence is often translated as simply "I do not drink tea." in English.
Because they can?
The topic marker is used to indicate the topic under discussion and can be used to add emphasis or imply contrast. Sometimes the topic is the same as the subject of the sentence, but it doesn't need to be. The topic could be the time or the location referenced by the sentence, or even the object of the verb.
When the direct object of a sentence is marked as the topic under discussion, は will replace を. This is similar to how は and が can swap with each other.
The meaning of the sentence doesn't change that much, but it is a little different, mostly a matter of emphasis. In addition to marking the topic, は is used to imply contrast. This sentence means "As for tea, (I) do not drink (it)" The grammar emphasizes that TEA is not something you drink, but also suggests there are probably other things you would drink.
An example of how this might work in conversation would be something like:
Person A: Would you like tea or coffee? Person B: Coffee, please. As for tea, I do not drink it.
Japanese has a past tense and a non-past tense. Depending on context, this statement could be referring to what you are doing right now or what you will be doing in the future.
Google translate tends to default to the future tense and it doesn't give you all the alternative readings that might make more sense for a particular sentence when read in-context.
The general endings are more of a "I will [in the future] do this" kind of feel... That being said, they use this to describe things that will happen in the immediate future so it's pretty much the same as them saying "I will do this right now," but true 'present' tense would be to change the verb into BaseTe+iru.
In order to standardize the terms used (and thus dispell confusion), lets just call the general endings as non-past (it being in the immediate future or in the distant future) and past. Then we can call the Bte+iru ending by the true title of 'present' tense.
No, the topic is tea, marked by は, the topic marker. The grammatical subject is implied. Notice that the Japanese sentence does not have 私 (I, myself) or が (subject marker).
The SUBJECT of a sentence is the person or thing that performs the verb's action. Another way to thing of the subject is as the actor or "doer" in the sentence.
In this sentence, the actor is implied. I am drinking the tea, so 私 is the doer of the verb's action.
(Ocha wa nomimasen.)
"As for tea, (I) do not drink (it)."
In this sentence, both the subject (I) and the direct object of the verb (it) are implied. We can safely assume that the speaker is the subject and that tea is the direct object of the verb, but neither one was clearly stated in the sentence. Tea was marked by は, so it is a topic, but its grammatical role in the sentence (direct object) was left unspoken.
You could also say it like this:
(Watashi ga ocha o nomimasen.)
"I do not drink tea."
In this sentence, the subject is clearly stated. It is grammatically correct, but would sound rather stilted in Japanese, since subjects are usually left out when they are easily inferred from context.
You could also say it like this:
( watashi wa ocha o nomimasen.)
"As for me, (I) do not drink tea."
In this sentence, the subject is implied. You might think that it is not implied, because 私 is right there, but notice that it is marked with は, not が. Since it is marked by は, watashi is the topic of this sentence. If the grammatical subject is also the topic, you mark it with は and leave the subject implied, just like when marking the direct object as a topic. You would not say it like this:
(Watashi wa watashi ga ocha o nomimasen.)
"As for me, I do not drink tea."
Saying it that way in English sounds fine, but in Japanese it sounds pretty dumb. If the topic or subject is obvious, you leave them out entirely. The subject is not considered necessary, like in English.
The same is true, to a certain extent, with the direct object.
(Ocha wa watashi ga ocha o nomimasen).
"As for tea, I do not drink tea."
If you have already used the direct object as a topic, you do not need to repeat it later on. Even in English, this sounds a little funny. Native English speakers would naturally replace "tea" with the pronoun "it" in that sentence. In Japanese, it would be more natural to drop "it" entirely.
Both sentences are polite. Leaving off subjects, like 私, does not change politeness level. In fact, it is so common to leave out 私 that it sounds weird (and kind of conceded) if you don't drop it.
You could say お茶を飲みます instead of お茶は飲みます, but these are also both polite. The difference is in the grammar, not the formality.
"As for tea, (I) don't drink (it)"
"(I) don't drink tea."
飲む (nomu) is the verb "to drink". 飲みます (nomimasu) is the polite form of nomu. It means the same thing as "nomu" but it is more polite. 飲みません (nomimasen) is the polite negative form "to not drink". And the casual negative form of this verb is 飲まない (nomanai). It means the same thing as the polite form, but it would be used in more casual settings.
Japanese uses various verb forms and auxiliary verbs to express various aspects of grammar like past-tense, present-tense, negative, passive, causative, and many more things.
I'm assuming は is used as a subject marker and を as an object marker. Based on that, I figured お茶を飲みません means "I do not drink tea" and お茶は飲みません would be "tea does not drink". I realize I'm probably missing a lot of information, so I hoped someone could help me with this one...
In general, for statements (not questions) where there was no previous context indicating a third person and there is a lack of honorifics, first-person would be assumed.
Unfortunately, with DuoLingo only providing one sentence at a time no previous context can easily be assumed or recognized. For the purposes of this program I would suggest that (lacking in-sentence context) most of these 'statement' sentences should be assumed to be first-person.
As far as when to use a first-person pronoun yourself, the same basic rules apply. Normally, within the context and flow of a conversation the subject will be clear. In cases where it might not be obvious one should use a pronoun for clarity.
Keep in mind, though, that once the subject is established and understood by both/all parties, it is unnecessary and unnatural to continue using the pronoun.