Many Spanish adverbs, as you have already seen, are formed by adding the suffix -mente to the feminine form of the adjective.
|Cristina habla rápidamente.||Cristina speaks quickly.|
|Iban a comer inmediatamente.||They were going to eat immediately.|
|Hacen el trabajo cuidadosamente.||They do the work carefully.|
As in English, many times the adverbs in -mente (corresponding to those in English -ly) are avoided by the use of prepositional phrases.
|por lo general||generally, in general|
|con esperanza||hopefully, with hope|
|sin duda||doubtless(-ly), without a doubt|
|por suerte||luckily, with luck|
When two or more adverbs ending in -mente are used together, the suffix is dropped on all but the last:
|Milagros hablaba clara, rápida y precisamente.||Milagros spoke clearly, quickly and precisely.|
Especially in speech, in both Spanish and English the adjective form (masculine singular) in Spanish may be used instead of an adverb (Como rápido, I eat quick[ly]), though this is not an impediment to comprehension.