Help with these sentences

[ZeRinku]

I was corrected on some of my Japanese sentences and I have some questions.

The first sentence was

万が一あなたは田中さんですか？
then I was corrected

もしかしてあなたは田中さんですか？

I was wondering why 万が一(by any chance) wouldn't work there...any help?

Then I wrote this sentence

万国はとってもきれいだな。

and she did not even understand what I was trying to say. I was trying to say that "all the countries in the would are very pretty, right?". I am not understanding what I did wrong there.

Another sentence

皆さん見れ、万引きだ！

then it was corrected to this

皆さん見て、万引きだ！

I knew when writing the sentence that using the -te form can make a command but there is a command form so I used it. So 見る became 見れ. Explanation of what I did wrong here?

Another...

その部屋に七人がいる。

then was corrected to

その部屋に七人いる。

I thought that the が was necessary here, no?

and another

彼は縄を下げる。

corrected to

彼は縄を下ろす。

No understanding the correction here either...

2nd to last one! Sorry!

俺はどこの。

corrected to

俺のはどこ。

She thought I was trying to say "where is mine". But I was actually trying to say "where am I?" with an explanatory の at the end, like I was asking somebody. What did I do wrong?

Last one!

たくさん水はいいです。

corrected to

たくさんの水はいいです。

She wasn't sure what I trying to say but she thought I was trying to say something about water being good for your health...and I meant to say "a lot of water is good" which good be interpreted as water is good for your health but why did she add the の there?

I'm sorry for so many questions but help would be greatly appreciated! Thank you.

[QuackingShoe]

万が一あなたは田中さんですか？
Because 万が一 is literally '10000 in 1 (chance)'. That doesn't make any sense here. もしかして is more like 'possibly'. Which is what you were trying to say. Don't rely on a strict 1-1 English-Japanese translations, IE the whole "By any chance..." thing. That's an idiomatic expression in English; it's not just going to carry over to another language like that.

万国はとってもきれいだな。
Can't say much about this as I'm not familiar with 万国. I'd agree that it doesn't sound right, but I can't tell you why exactly. Although, I'm not sure why you'd call countries pretty, anyway. Ending an adjective sentence with だな is pretty forceful and informal, though, by the by.

皆さん見れ、万引きだ！
That verbal form is really direct and rude. You're really ordering someone to do something instead of asking, let alone asking nicely.

その部屋に七人がいる。
Counters are only really numbers and only really stand up as subjects when a number would. So they can be used to directly count other nouns, like 七人の侍, but... they can also be used somewhere before the verb to count how many of the relevant noun are doing the action. That's what you need here. So the phrase is like 人が七人いる or whatever, but we're doing our usual subject drop. So it's just 七人いる。 That's afaik, anyway.

彼は縄を下げる。
下げる is like hanging or lowering (from something). 下ろす（おろす） means to take something down, drop something, let someone off, unload, etc. It's what you meant.

俺はどこの。
You're trying to work an English sentence into a Japanese sentence again, in this case "I = where?" That'd probably be understood normally, but your の is making it more confusing (especially as there's no question mark or particle). What you're basically saying is "As for me, where's (possessive). As if where owns something. She corrected it to "As for mine, where."
The standard way to say what you wanted to say, though, is ここはどこ？ Here = where?
As misc commentary, 俺 isn't a very polite personal pronoun either. 私 or 僕 are significantly more acceptable, especially in mixed company.

たくさん水はいいです。
This is hard to explain. For one thing, for takusan (or most anything that isn't an -i adjective) to modify a noun, you need to connect it with の or　な (depending on blah blah blah). Right now it's kindof modifying the いい as an adverb, I guess, which really doesn't make any sense. Personally, I'm not sure what "a lot of water is good" means either. Like, for a lake? For drinking? What? If you mean drinking a lot of water is good for you, you'd say something like 水をたくさん飲むというのは体にいいです。 Well, at least that's how I'd try to say it. The grammar there might be a little complex though. Basically, "The thing called drinking lots of water is good for your body." There are shorter ways to say it, especially since nobody likes to say anything that long, but I think that's the basic, unambiguous expression. You can be more polite with an お水. If you just wanted to literally say that a lot of water is preferable to you for some reason, I'd use 多い instead of たくさん... but I could be horribly wrong

You should try to see if you can't find some grammar resources online, or books you can buy. And remember, English and Japanese are very different languages; don't try to compose one while using the other.

Good luck!

[Belton]

The first sentence was

万が一あなたは田中さんですか？
then I was corrected

もしかしてあなたは田中さんですか？

I was wondering why 万が一(by any chance) wouldn't work there...any help?

万が一 is 10,000 to 1 (odds) and seems to carry the notion of if by any chance.
Edicts entry is a little unclear, but the examples are all about unlikely events and an outcome.
It's a mismatch of english padding phrase and how Japanese politely soften the otherwise blunt question Are you so and so?

Then I wrote this sentence

万国はとってもきれいだな。

and she did not even understand what I was trying to say. I was trying to say that "all the countries in the would are very pretty, right?". I am not understanding what I did wrong there.

dictionary problems again.
万国 is more like "International" than "all countries".
I find it best to run the Japanese word I find back through the dictionary and look at example usage as well. I also use the Ejiro dictionaries as well as Edict.

世界各国 might be closer

皆さん見れ、万引きだ！

then it was corrected to this

皆さん見て、万引きだ！

The imperative is too harsh　even in this situation of drawing attention to a shoplifter.
I think it's for the military and small naughty children (笑）

その部屋に七人がいる。

then was corrected to

その部屋に七人いる。

I thought that the が was necessary here, no?

It would be if you had specified a subject, for instance
その部屋に侍が七人いる。

七人 is a counter rather than a number modifying a noun like an adjective.
その部屋に本が七冊ある。
その部屋にCDが七枚ある。

so the sentence could actually be
その部屋に人が七人いる。
人が　is implicit and left out.

彼は縄を下げる。

corrected to

彼は縄を下ろす。

下ろす may just be what you do to ropes, and 下げる is what you do to heads (bowing) but seems to have the meaning of decrease more often that physically lower or drop something.

俺はどこの。

corrected to

俺のはどこ。

She thought I was trying to say "where is mine". But I was actually trying to say "where am I?" with an explanatory の at the end, like I was asking somebody. What did I do wrong?

The の might be too feminine sounding perhaps and hence not fit with the masculine 俺
俺はどこ? might be closer

たくさん水はいいです。

corrected to

たくさんの水はいいです。

She wasn't sure what I trying to say but she thought I was trying to say something about water being good for your health...and I meant to say "a lot of water is good" which good be interpreted as water is good for your health but why did she add the の there?

I would have thought either would work. Maybe it depends on whether たくさん　is behaving as a noun or an adverb. Here it can't really work as an abverb so to modify a noun with a noun you use の

you probably should be clearer about how the water is good. good in what way? good for what? even in English it's a bit unclear and weak.

I'm sorry for so many questions but help would be greatly appreciated! Thank you.

They are interesting points I think. 勉強になりました。

[Psy]

俺はどこの。

corrected to

俺のはどこ。

She thought I was trying to say "where is mine". But I was actually trying to say "where am I?" with an explanatory の at the end, like I was asking somebody. What did I do wrong?

The の might be too feminine sounding perhaps and hence not fit with the masculine 俺
俺はどこ? might be closer

Before anyone gets more confused, I'm going to paraphrase what Belton wrote above (trust him, people! He's been around the block a few times...) and say that for "where am I" the Japanese do not say 俺／私／僕はどこ？ It's one of those things that sounds like it should be correct, and while there's nothing wrong with it from a grammatical standpoint, nobody says it that way in real life. Kind of like how no one asks "where is here?" in English. The proper way to ask is 「ここ、どこ？」 or 「ここはどこ？」 or 「ここはどこですか？」 or some variant.

For "all the countries of the world are beautiful," I would say 「世界中の国はすべて、綺麗なところがありますね」, though I can't vouch for its correctness. 「万国」 just sounds newspaperish to me, and using it outside of formal settings just seems to clash with the conversational tone.

Just my humble 視点. 間違いとこがあったらどうぞ直してください。

[Belton]

(trust him, people! He's been around the block a few times...)

I'm not sure how to take that. ???

The sentences sound like they're from a ninja story or manga perhaps.

Here the stylistic intention would seem to be an arrogant male asking himself where the heck he is. The question would be how to get that in to a short utterance. どこ？　by itself doesn't seem enough.

(everything I say is mere opinion, and just reflects my own often flawed approach.)

-- edit added later after a Google search made in curiosity.
http://www.youtube.com/watch?v=Xhj0FqQ91tU
not the best example but examples of native usage of 俺はどこ？ can be found. interestingly here alongside ここはどこ？

not that common in my search but it's there.

another from a blog--
透明度は２センチありましぇーーん。指の第一間接まで漬けたらもう爪が見えましぇーーん。
　どれ、さっそくジャボンと・・・うほー久々、おもろい～。俺はどこ？　俺の手、どこ？　あはははは～。さあみんなで笑おうあはははは。

most people seem to be asking themselves 俺はどこへ行く？

[ZeRinku]

ありがとうございます！

I will admit some of the stuff is a still fuzzy to me but I have a better understanding of what I did wrong. Well...back to Tae Kim's guide!

[Rod Wadd]

皆さん見れ、万引きだ！

then it was corrected to this

皆さん見て、万引きだ！

Google seemed a bit iffy on 見れ, but isn't　見ろ the imperative form of 見る？

You can be more polite with an お水.

　Isn't using お水 a bit effeminate?

[Belton]

but isn't　見ろ the imperative form of 見る？

You are quite right.
ichidan goes 〜る to 〜ろ　　 見る、見ろ
godan goes 〜る to 〜れ　　　頑張る、頑張れ

I missed it because of what I expected to see 笑

{quote}Isn't using お水 a bit effeminate?[/quote]
perhaps, it depends who's saying it.
I would use お水 for drinking water. There's no need to be boorish.
ditto お茶、お酒、ご飯、
but a male character who'd refer to himself with 俺 might not.
but then I'd say he wouldn't pair it with です
In general women use much more polite speech than men. but polite isn't feminine in and of itself.