‘And’ or ‘Or’?
Incorrect : He did not speak loudly and clearly.
Correct : He did not speak loudly or clearly.
Note: You can say "He spoke loudly and clearly”. But if a negator is used in a sentence, the conjunction “and” should be replaced by "or". However, if clauses with different subjects are joined in a sentence, the conjunction "and" may be used in a negative sentence in this way:
She did not respond to my letter, and I did not feel good at all.
In this case, a comma is necessary before “and”.