すむ/済む(sumu): to get off with/be settled
すみます(sumimasu); the polite form of "sumu"
すみません(sumimasen); the negative form of "sumimasu"
"Sumimasen" is from "(あなたの行為に対して)私の気が済みません; (anata no koui ni taishite) watashi no ki ga sumimasen", which literally means "I'm not satisfied (with my reaction for your action)"
> In most text books
I'm using NHK's 'Japan My Love' programme. It's the only learning aid (I printed the manual as well) I have at the moment (the mp3s are extremely useful as I can walk around practising, although it can be a bit dangerous...). I intend to work my way through it and not acquire anything else until I've done so; for the sake of not getting confused.
The thing it lacks is some one to ask; but asking in here has already been very useful.
I think you might be better to learn the grammar of Japanese. Probably it's hard to understand the difference among the following sentences without it.
パスポートが落ちました。; Pasupo-to ga ochimashita.
The passport has fallen.
パスポートが落ちましたよ。; Pasupo-to ga ochimashita yo.
You've dropped your passport.
パスポートが落ちますよ。; Pasupo-to ga ochimasu yo.
Please be careful to not drop your passport.
パスポートが落ちてました(よ)。; Pasupo-to ga ochitemashita (yo).
I saw the passport fallen (on somewhere).
or with holding out it for the listner
I found this passport (on somewhere).
パスポートを落としました。; Pasupo-to wo otoshimashita.
I dropped my passport.
パスポートを落としましたよ。; Pasupo-to wo otoshimashita yo.
You've dropped your passport.
Another question (promise, no more for a while): NHK's programme has dōmo arigatō gozaimasu and they shorten this to dōmo arigatō or simply arigatō depending on circumstances/situation but I've never heard any anime use dōmo; plenty of arigatō gozaimasu's and arigatō's but I can't recall ever hearing dōmo in front. So when would one add dōmo?
Watashi sounds much nicer (IMO) than the alternatives anyway, but, here again NHK seems to suggest that men should use boku (and animes do use watashi and boku fairly consistently as female/male, old men as well; well those I've watched anyway). Hmmmm....
I get the formal/informal thing and context (well, I think I do); after all you can do English that way if you want.
I also use "watashi" at work, and frequently "doumo". Just you haven't heard it yet. "Doumo" is often used even in anime, of course.;-)