japanese polite speech to casual speech help?

Was it quiet, wasn't it?

a) Shizuka datta ne? (casual, both male/female)
b) Shizuka datta yo ne? (same above, a bit childish)
c) Shizuka datta desu yo ne?(more polite)

shizukatane ..... improper use



Is it quiet?

a) Shizuka ? (most casual, both male/female)
b) Shizuka desu ka? (polite)

There are just few example. Each expression may vary one by one case by case on the individual situation in Japanese.

Desu ---- be(polite, decent), present tense.
Da(or dearu) ------- be(rough, indecent), present tense(or was/were = past tense)

Deshita --- was/were(polite, decent) and/or its past perfect tense
Datta ----- was/were(rough, literary) and/or its past perfect tense

She is a maid.
Kanojyo wa maid desu. (polite)
Kanojyo wa maid dearu. (rough, literary)(usually by elder male)
Kanojyo wa maid da.(rough, casual)(rather by male)
Kanojyo wa maid.(most casual)

She is a maid, isn't she?
Kanojyo wa maid desu yo ne?(polite, decent)
Kanojyo wa maid da yo ne?(rough, casual)
Kanojyo maid?(most casual)

She was a maid, wasn't she?
Kanojyo wa maid deshita yo ne?(polite, decent)
Kanojyo wa maid datta yo ne?(rough, casual)
Kanojyo maid datta?(most casual)

> desuka ---- datta
> (na adj) shizukadesune ----- shizukatane

desuka doesn't correspond to datta

desu in non-past, polite
the added "ka" is for a question

datta is past, neutral

The equivalent of "shizuka desu ne" would be "shizuka datta ne"

I'm not going to write a grammar essay here, so just a few examples:

It's hot: (atsui, an adjective)

Polite: atsui desu.
Neutral: atsui
Past, polite: atsukatta desu
Past, neutral: atsukatta

It's calm (shizuka, a nominal adjective)

Polite: shizuka desu.
Neutral: shizuka da
Past, polite: shizuka deshita
Past, neutral: shizuka datta.

Verb: to eat

Polite: tabemasu.
Neutral: taberu.
Past, polite: tabemashita.
Past, neutral: tabeta.

Verb: to read

Polite: yomimasu.
Neutral: yomu.
Past, polite: yomimashita.
Past, neutral: yonda

There is more to it of course, and you also have the choice of words, the possible omission of part of the particles in neutral speech (choko, taberu?), etc.