知っていれば

if (someone) knows

→ 知る
phrase Rare #21,698
if (someone) knows The subject is usually understood from context; it can also mean “if (someone) knew” in a hypothetical situation.
JA: 場所を知っていれば、案内できます。
EN: If I know the place, I can show you the way.

ちょっと言葉を知っていればずいぶん役にたつよ。

It helps a lot if you know just a few words.

外国語を知っていれば有利である事が君にもわかるでしょう。

You can see that knowing a foreign language is advantageous too.

知っていれば教えてあげたんだけど。

I would have told you if I’d known.

もし君の住所を知っていれば、彼女は君に手紙を書くだろうに。

If she knew your address, she would write you a letter.

もし彼の住所を、知っていれば手紙が書けるのだが。

If I knew his address, I could write him a letter.

仮に知っていれば私たちに話すだろう。

If they knew, they would tell us.

真実を知っていれば、君に話すだろう。

If I knew the truth, I would tell you.

もし彼女の住所を知っていれば、手紙を書くのだが。

If I knew her address, I would write her a letter.

知っていれば私たちに話すだろう。

If he knew, he would tell us.