-desu or -masu? (Japanese)?

Question

I found this phrase on another website, (Kuruma ga hoshii desu. I want a car.) and I was wondering why it isn't "Kuruma ga hoshii masu." Why isn't it -masu?

And another thing, how do you conjugate de aru? And for verbs with "suru" at the end (not just suru by itself, but verbs that have suru) do you just conjugate suru? Thanks. (I must be getting annoying, sorry! I have so many questions.)

So, if I said, "Watashi wa nihongo hanashimasu" could I use -desu instead of -masu?

Answer 1

Just remember that "masu" is used with verbs, whereas "desu" is used with nouns and adjectives.

Now, let us take a look at the example you have given. Even though "want" is a verb in English, "hoshii" is an adjective in Japanese. Thus, we use "desu".

Next, the conjugation of "de aru" is as follows:
- dewa nai (ではない)
- de arimasu (であります)
- de aru (である)
- de areba (であれば)
- de arou (であろう)
- de attte (であって)

As for the suru verbs that you mentioned, do you mean "benkyou suru", "junbi suru", "seikatsu suru" etc? Well, you just conjugate "suru" will do. Here's an example:
- benkyou shinai (勉強しない)
- benkyou shimasu (勉強します)
- benkyou suru (勉強する)
- benkyou sureba (勉強すれば)
- benkyou shiyou (勉強しよう)
- benkyou shite (勉強して)

Hope this helps. ^_^

Answer 2

-Masu is used for ru/u verbs. Iku, kuru, suru, hanasu, oyogu... those are all verbs. -Masu is never used just by itself.
Desu is used for everything else.

Aru becomes "arimasu" just like iru becomes "imasu".
Suru becomes shimasu.
If by "verbs with suru at the end" you mean things like "benkyou suru" then, yes, you just change suru to shimasu.

You cannot have them together because it makes absolutely no sense. Both are polite sentence enders and have specific things they go to. They just do not go together at all. It's simply the way Japanese is.

First, it should be "nihongo wo hanashimasu" and you cannot say "nihongo o hanasu desu" because it makes no sense. It's like saying "Japanese language speak" in English. No one would have a clue what you're on about.
Hanasu is a verb and all verbs become -masu. The only time a verb even glances at desu is if it's something like "hanashitai" (I want to talk). Otherwise it's -masu.

Also, you ask a lot of really basic Japanese questions. Japanese is a well known language and places like http://www.guidetojapanese.org/
http://www.jgram.org/
http://www.thejapanesepage.com/
are probably what you should be taking a look at.

Answer 3

because at the end of a statement, desu is always used at the end of the sentence. kind of to destinguish that its a statment.
sry about the second question.

Answer 4

It's all related to verb and noun wording.