〜を通じて／を通して

友人(ゆうじん)を通(つう)じて彼(かれ)を知(し)りました。

Yūjin o tsūjite kare o shirimashita.

I came to know him through a friend.

The first sense is by way of an intermediary

日本(にっぽん)は一(いち)年(ねん)を通(つう)じて雨(あめ)が多(おお)いです。

Nihon wa ichinen o tsūjite ame ga ōi desu.

Japan gets a lot of rain all year round.

The second is throughout a period, on a time noun

二(ふた)つはほぼ同(おな)じで、後者(こうしゃ)のほうが口語(こうご)寄(よ)りです。

Futatsu wa hobo onaji de, kōsha no hō ga kōgo yori desu.

The two are near-identical, the second more spoken.

Writing leans を通じて, but swapping them rarely misfires