on

preposition:in contact with and supported by a surface
- The book is on the table.
preposition:concerning or about a subject or topic
- She gave a talk on renewable energy.
preposition:using or by means of a device, platform, or system
- He watched the game on his phone.
preposition:scheduled for or occurring during a particular day or date
- The interview is on Monday.
preposition:at the time of or immediately after
- On arriving home, I realized I had lost my keys.
preposition:carried by, worn by, or attached to someone
- He had no cash on him.
preposition:engaged in or performing a particular activity or duty
- The nurse is on duty tonight.
preposition:taking or being treated with a particular medication or regimen
- She is on antibiotics for a week.
adjective:operating or switched to an active state
- The lights are on.
adjective:happening, available, or in progress
- The show is on at eight.
adverb:continuing or onward in time or activity
- The rain went on all night.
preposition:paid for by
- The drinks are on me tonight.