Question

What is the difference between by at on off? Clarify with the examples and how to when to use in a sentences properly!

Answer 1

'by' is a preposition which means-1) through the action of.
eg:- Ram finally took her by the arm. 
'at' is a preposition which -1) expresses a location in the particular place (or)
                                             2) expresses a time when a particular event takes place.
It is used for a precise time.
eg:- the children go to bed 'at' nine o' clock.
'on' is a preposition which means-1) into contact with something.
It is used for days and dates.
eg:- on Sunday.
'off'  is an adjective which means-1) away from a place (or)
                                                         2) to be discontinued.
eg:- the man ran off.  Switch off the lights. etc.