warn

bluntly

The teacher bluntly warned us that anyone caught cheating would fail the entire course.

softly

My mother warned softly that we should leave before the storm arrived.

specifically

The teacher specifically warned us that the exam would be very difficult.

duly

The lifeguard duly warned swimmers about the dangerous currents before the beach opened.

constantly, repeatedly

His doctor repeatedly warned him about the dangers of smoking before his heart attack.

had better, have to, must, should

I have to warn you that the bridge ahead is closed for repairs.

try to

My teacher tried to warn us about the difficult test, but we didn't listen.

fail to

The company failed to warn customers about the product defect before it was released.

about

The teacher warned the students about the difficult exam coming next week.

against

The doctor warned me against eating too much salt because of my high blood pressure.

of

The weather service warned of severe storms heading toward the coast this evening.

be warned

Be warned that the new software update will take several hours to install.