By as an adverb in a sentence

OF, ABOUT, FOR, WITH, BY

OF:

Of expresses the relationship of a part of something to its whole. It is the most used preposition in English.

Example.

• He is a boy of 15.
• Some parts of his body were injured.
• Most of the guests are gone.
• The plays of Shakespeare will always be classics.

ABOUT:

About means ‘on the subject of’ something or ‘concerning of’ something/someone.

It also means ‘approximately.'

Example:

• I was about to leave.
• He cares about his classes.
• I have about 30 candies in my bag.
• This article is about computers.

 FOR:

For means ‘with the object or purpose of’.

It indicates a suiting of purpose for something/someone.

Example:

• I will always be here for you.
• I have done it for my benefit.
• Cucumber is a good vegetable for making a salad.
• Take my gratitude for your kind hospitality.

WITH:

With means ‘accompanied by’ something or someone.

Example:

• I will always be with you.
• I have brought some candies with me.
• He
  use by in sentences
  by word use in sentence