GRAMMATICAL RULES OF ADVERBS

1. The general rule for forming adverbs is to add the ending "-ly" to an adjective, which is equivalent to the ending in Spanish of ("-mente").
Examples:

     quick →   quickly(rápido → rápidamente)
     honest →   honestly(honrado → honradamente)

2. For adjectives that end in a consonant + "-y," "-y" is changed to "-ily."
Examples:

     easy →   easily(fácil → fácilmente)
     happy →   happily(alegre → alegremente)

3. Adjectives ending in "-ic" the ending "-ic" is changed to "-ically."
Examples:

     automatic →   automatically(automático → automáticamente)
     tragic →   tragically(trágico → trágicamente)

4. Adjectives ending in "-le," the ending "-le" is changed to "-ly."
Examples:

     terrible →   terribly(terrible → terriblemente)
     incredible →   incredibly( increíble → increíblemente)

5. Some irregular adverbs do not end in "-ly."
Examples

     hard(difícil, duro o fuerte)
     fast(rápido)