What are Prepositions
Prepositions are those words, which show the relationship of Nouns (or Pronouns) with the other words in the sentence. Prepositions are used before Nouns (or Pronouns) in the sentence.
Behind is used to refer to an item at the back side of something. Behind is also used to show the lower level of an item than the others and behind is also used to refer to the past.
Look! There is something behind you.
She was standing behind the door.
There may be a dog behind the gate.
There is a cunning person behind his innocent face.
You are hiding your pain behind your smile.
You are lagging behind.
Leave behind all your sorrows and cheer.