On most frequently has a literal, spatial sense; either static (be / lie / sit / sprawl / stand / stay / wait, etc. on the bus / on a bed / on a bike / on a chair / on a horse / on a plane / on the platform / on a train, or with movement: climb on the wall / get on the bus / jump on the train / put a book on the shelf. With verbs of movement, it is also possible to use onto instead of on , particularly if some difficulty is involved:
We can say that someone is on holiday / on a journey / on a trek / on a cruise / ona trip / travelling on business / on a training course, and that someone is on a board of directors / on a committee / on a panel / on a short list. We can take on work or responsibility for someone or something, while obligations, tax and so on can be imposed on people, or be incumbent on people:
Verbs followed by on, with no change in meaning to the verb, include concentrate / congratulate someone / depend / insist / rely on someone or something. We can also be dependent or reliant on someone or something.
Similarly, we talk about a dependence / reliance / insistence on something and and give someone our congratulations on something:
Off With a number of verbs, off is simply the opposite of on : switch / turn off lights, the TV, the heating, etc / jump off (or on ) a platform / go off (or come on ) stage; take clothes off (or put them on).
After verbs of motion, off can mean away :
After a few verbs, off can suggest a decline. Food can go off (go bad), numbers can drop off or fall of f (go down).
The Grammar blog is written by Stephen Smith, who has been a teacher with OISE for over 10 years.