The pronoun ‘en’

The pronoun ‘en’ replaces :
1. de + noun
2. du + noun
3. de la + noun
4. de l’ + noun
5. des + noun
6. definite quantity + noun
   6.1 The definite quantity should be mentioned in the affirmative sentence.
   6.2 The definite quantitive shoud not be mentioned in the negative sentence.
7. indefinite quantity + noun
   The indefinite quantity should be mentioned both in the affirmative and negative  sentence. 

NOTE : Generally ‘en’ will not replace a person except with definite quantity.