告诫 (gào jiè): 경고하다.

My mother warned me repeatedly that when crossing the road I must watch the traffic lights and not look down at my phone.

The doctor warned him that if he didn't quit smoking and drinking, his liver problem would become increasingly serious.

Before setting off, the tour guide warned everyone that the weather in the mountains changes quickly and they must bring raincoats and thick coats.

The teacher warned the students not to cheat during the exam, otherwise their scores would be cancelled.

My father warned me that before lending money to others, I must think it through carefully, because some money may never be paid back.