I have to catch a train at 7 o'clock.
Catch one's breath.
Word: "catch"
different meanings

Float a ship.
The government floated the ruble for a few months.
Word: "float"
different meanings

The accident was a good lesson to me.
He did the lesson for today.
Word: "lesson"
different meanings

Guard against infection.
Guard against becoming too friendly with the staff.
Word: "guard"
the same meaning