Undecided questions
Translate this in japanese my sentence is: You know how important he/she to me

あなたは私に大切な彼女を知っている。if you take it literally. This is for "she".

You know how important she/he is to me= kare/kanojo wa watashi/atashi/boku/ore nitotte dore hodo daiji na hito dearu koto wo, kimi/anata/omae wa shitteiru deshou/darou. 彼/彼女は私/あたし/ボク俺/にとってどれほど大事な人であることを、君/あなた/おまえは知っているでしょう/だろう。

彼 kare= he
彼女 kanojo= she
kimi= you (informal)
anata= formal
omae( informal, among men)
watashi= I (neutral, not very formal, not very informal)
atashi= I ( informal for girls)
boku= I ( informal/humble for boys)
ore= I (kinda rude/informal for men)
deshou (a little formal)
darou( more informal than deshou)

In Japanese you cannot simply translate a sentence and that's it, you have to specify who speaks and to whom you speak, that includes gender and formality.

You know how important she/he is to me= kare/kanojo wa watashi/atashi/boku/ore nitotte dore hodo daiji na hito dearu koto wo, kimi/anata/omae wa shitteiru deshou/darou. 彼/彼女は私/あたし/ボク俺/にとってどれほど大事な人であることを、君/あなた/おまえは知っているでしょう/だろう。

彼 kare= he
彼女 kanojo= she
kimi= you (informal)
anata= formal
omae( informal, among men)
watashi= I (neutral, not very formal, not very informal)
atashi= I ( informal for girls)
boku= I ( informal/humble for boys)
ore= I (kinda rude/informal for men)
deshou (a little formal)
darou( more informal than deshou)

In Japanese you cannot simply translate a sentence and that's it, you have to specify who speaks and to whom you speak, that includes gender and formality.

Kare/kanojo wa watashi/atashi/boku/ore nitotte dore hodo daiji na hito dearu koto wo, kimi/anata/omae wa shitteiru deshou/darou. 彼/彼女は私/あたし/ボク俺/にとってどれほど大事な人であることを、君/あなた/おまえは知っているでしょう/だろう。

彼 kare= he
彼女 kanojo= she
kimi= you (informal)
anata= formal
omae( informal, among men)
watashi= I (neutral, not very formal, not very informal)
atashi= I ( informal for girls)
boku= I ( informal/humble for boys)
ore= I (kinda rude/informal for men)
deshou (a little formal)
darou( more informal than deshou)
In Japanese you cannot simply translate a sentence and that's it, you have to specify who speaks and to whom you speak, that includes gender and formality.

Kare/kanojo wa watashi/atashi/boku/ore nitotte dore hodo daiji na hito dearu koto wo, kimi/anata/omae wa shitteiru deshou/darou. 彼/彼女は私/あたし/ボク俺/にとってどれほど大事な人であることを、君/あなた/おまえは知っているでしょう/だろう。

Explanation in next post.

あなたは彼女が私にとってどれぐらい大切だと知っている

彼のことが、どれだけ大切か知ってるよね。
（kareno kotoga doredake taisetuka sitteru yone）
彼がどれだけ私にとって大切か知ってるでしょ。
(karega doredake watashini tottte taisetuka sitteru desho)
どれだけ、彼が私にとって大切かわかるでしょ。
(doredake karega watasini totte taisetuka wakaru desho)