What is "It is x o'clock" in Japanese with subject


I've just started studying Japanese so I'm using Hiragana.  
In the book it says  

> "It's 1 o'clock"

is

> "いちじです"

in Japanese.  
But if I want to use the form

> "X はいちじです"

then what should "X" be?




Most formally, we say:

> 「只今{ただいま}の時刻{じこく} + は + X時{じ}です。」

To continue roughly in the order of formality, we replace 「只今の時刻」 by:

> 「現在{げんざい}の時刻」
>
> 「今{いま}の時刻」
>
> 「今」

Please remember, however, that just saying 「X時です。」 is completely grammatical,
normal, common, natural-sounding, etc. in Japanese.

Finally, by replacing the 「時刻{じこく}」 by 「時間{じかん}」 in the phrases above, they
become slightly less formal as well.




Most formally, we say:

> 「只今{ただいま}の時刻{じこく} + は + X時{じ}です。」

To continue roughly in the order of formality, we replace 「只今の時刻」 by:

> 「現在{げんざい}の時刻」
>
> 「今{いま}の時刻」
>
> 「今」

Please remember, however, that just saying 「X時です。」 is completely grammatical,
normal, common, natural-sounding, etc. in Japanese.

Finally, by replacing the 「時刻{じこく}」 by 「時間{じかん}」 in the phrases above, they
become slightly less formal as well.

