I have seen that the word "I" has been omitted from many sentences here.
"ジョンです" 訳: I am John. I think that 'わたしは、ジョンです。' is better to translate as 'I am John'. Indeed, we often omit 'わたしは'. However, "ジョンです。" alone does not understand the subject word.
If 'ジョンです' is the question, 'It is John', 'He is John' may also be correct.
- I have the opportunity to use 'watasiha/ga'.
I am worried that some people believe that "watasi ha/ga" must be omitted. Certainly Japanese often omit "watasi ha/ga". However, it is not absolute. You can use 'watasi ha/ga'.
ノーベル賞受賞会見挨拶 Message from the Nobel Prize winner. http://news.mynavi.jp/articles/2016/10/04/ohsumi_nobelprize/
Why do you think that the word "Watashi ha/ga" exists? Because it is used. There are natural situations that "watasi ha/ga" uses. I think people who have already acquired Japanese language omit the subject "watasi ha/ga" can freely. But please do not deny other people who use "watasi ha/ga". So I think it is good that Duolingo add the answer the sentence include 'watasiha/ga'.
in Japanese many time you relay on the conversation before, you usually don't use "i" in Japanese because people understand you're talking about yourself. it is not natural to use "i" many times. in the example you gave it is especially unnatural because you're introducing yourself so in Japanese it turns out like you talk about yourself twice. in short you don't need to use "i" in Japanese because people usually understand that you're talking about yourself and if they don't they'll ask you, it's more natural than to add "i".
English speakers know (at least they should know) where to put "I" and other pronouns. It's better to teach them natural Japanese. Yes, ジョンです is ambiguous, but that's how many natural sentences look like and you need to learn to understand them if you're learning Japanese.
Adding extra わたしは everywhere makes more sense in a course for Japanese speakers, so they can learn what "I" means and not use "I" where it shouldn't be used.
I agree. The problem here is that this course of Duolingo does a lot natural language sentences that require context to truly translate or understand.
"ジョンです" requires context that the leaner does not have. Yes in the context of a conversation, the Japanese person would leave out "わたしは" but only if that was clearly implied from the conversation.
English speakers leave out the understood "I" often too. But again only when the context is clear.
If I just stood in the middle of a room and shouted "John!" nobody would have any idea what I was talking about. Am I John? Am I looking for John? Who knows?
At the very least (like many language learning courses) if there is a part of the sentence that is implied or understood, the implied or understood portion could be supplied in parentheses so that the learner knows that saying the parenthetical portion is unnecessary but that it is implied. It would be much clearer here:
E: (I am) John J: (わたしは) ジョンです
You'll also find that in polite conversation, people generally tend not to use pronouns. I've even heard a fair few conversations where people just flat out speak in the third person. I found something about this on Tae Kim's grammar guide, and I guess it's actually a thing. From what I understand, it's not as polite to use pronouns because it's regarded as an impersonal way to single someone out. The whole speaking in the third person thing comes into play to make the conversation more personal, like "oh hey I remembered your name".
On the complete opposite side of the spectrum, there's a million different casual pronouns that you'll regularly hear in anime. So, maybe this is an issue of tailoring your conversation to your audience?
Refs: took the N4 and failed it, been to Japan twice
Thank you. In some answers of Duolingo, there are 'わたしは' is including. Some people will be confusing, why the word 'わたしは' shows up.
I know the word frequently omit. Certainly 'わたしは' is not need in all sentences. But just I want to say that to use the word is no problem.
I am glad I hear many opinions.