忽然 (hū rán): ทันใดนั้น; จู่ๆ

I suddenly remembered that I forgot to bring my keys.

He suddenly ran out, and I couldn't catch up with him.

It suddenly started raining heavily, so we had to go home.

She suddenly laughed, which surprised me.

The teacher suddenly asked a question, and I felt a bit nervous.

He suddenly remembered something.

Suddenly, it started to rain heavily.

She suddenly started laughing.

Suddenly, the light went out.