自从 (ever since)

Start the clock in the past

• ((bound form) self自zì)from从cóng … = "ever since (a past starting point)".
• since (a time)自从zì cóngto arrive来到lái dàohere这儿zhè ér，I / me我wǒvery很hěnto feel happy开心kāi xīn = "ever since I came here, I've been happy."
• It opens with a past event and tracks the change after it.

since (a time)自从zì cóng + Past Event，…

• since (a time)自从zì cóng marks the moment a new state began.

ever since自从zì cóngcome来láihere这儿zhèr，I我wǒvery很hěnhappy开心kāi xīn。

• since (a time)自从zì cóngto come来láihere这儿zhè ér，I / me我wǒvery很hěnto feel happy开心kāi xīn = "ever since I came here, I've been happy."

Recap

Read the full reference: HSK 5 grammar — Prepositions.