"A man walks."
Yup! They serve similar roles. 는 adds the feeling of stressing this particular one. So this particular man walks. Maybe the other men drive their cars. Using 가 would not give that feeling, but other than that the sentences would be the same :)
In this sense, shouldn't it rather be 가, as the English sentence says 'A man', thereby not stressing the man at all?
I think it's the other way around:
- 는 - Topic marker, used after a vowel e.g. 여자는 - A woman. Used when making a general statement e.g. An apple is a fruit.
- 은 - Topic marker, after a consonant e.g. 연필은 - A pencil.
- 가 - Subject marker, used after a vowel e.g. 학교가 - The school
- 이 - Subject marker, used after a consonant e.g. 연필이 - The pencil. Used when you're talking about something specific e.g. THE pencil is a thing
걷 is the root from 걷다. Because it ends with a consonant, it gets -습니다 appended to it.
In contrast, 가다 (to go) ends with a vowel so only gets -ㅂ니다, i.e. 갑니다.
I put '남자는 걷습니다..' and it was marked wrong. The correct one was '남자는 걷습니다.' The wrong part was that one friggin dot on my sentence. Reported.
A little late to the party, but I put "남자가 갑니다" and it marked me wrong. I've read through the comments that have been posted for over a year and this still hasn't been fixed. Shouldn't we be able to add "-가" as it has a similar meaning to "-는"?