唯 (wéi): chỉ có

After his parents passed away, he became the only support in the family, working two jobs every day to pay for his younger sister's schooling.

In this exam I got only one question wrong; my only regret is that I forgot to write my name and lost five points.

He is the only one in the company who can repair this old machine; he is the sole technician capable of fixing this malfunction.

Everyone in the class handed in their homework; only Li Ming hadn't. When the teacher asked why, he said he was sick yesterday.

On this trip, the only thing that disappointed me was the constantly gloomy weather, so I couldn't see the sunrise.