A or An

Use “a” when the first letter of the word following has the sound of a consonant. Keep in mind that some vowels sound like consonants when they’re sounded out as individual letters.

Examples:
a frog
a hospital
a universe

Use “an” when the first letter of the word following has the sound of a vowel. Remember that some consonants sound like vowels when they’re spoken as individual letters.

Examples:
an FBI case (“F” is pronounced “ef” here)
an honesty (“H” is silent here)
an unreal idea

Deciding whether to use “a” or “an” before abbreviations can be trickier. The abbreviation for “Frequently Asked Questions (FAQ)” causes confusion because it can be pronounced as a word (fak), or one letter at a time (F-A-Q). Using the guidelines above, one would say "a FAQ" when it is pronounced as one word, and "an FAQ" when it is pronounced one letter at a time.

Examples:
an FBI agent (“F” is pronounced “ef” here)
a FICA tax decrease
an HMO plan (“H” is pronounced “aych” here)
a HUD program
an NAACP convention (“N” is pronounced “en” here)
a NASA study

bibliografia: The Blue Book of grammar and punctuation by Jane Strauss

Adverbs

What's an adverb?

Modifier of verb or adjective: a word that modifies a verb, an adjective, another adverb, or a sentence, e.g. "happily," "very," or "frankly"
[15th century. Directly or via French < Latin adverbium (after Greek epirrhēma "added word")]
adjective or adverb?
Some adjectives are used as adverbs without changing their form: a fast car; You're driving too fast. Other adjectives can be used as adverbs, instead of the -ly adverb form, in a restricted range of contexts: Hold on tight [or tightly]. He spelled my name wrong [or wrongly]. In most cases, however, it is incorrect to use an adjective as an adverb: I want it badly [not bad]. She was really [not real] pleased.

Microsoft® Encarta® 2007. © 1993-2006 Microsoft Corporation. Reservados todos los derechos.

Formation

Adverbs can be:

1. natural adverbs:

in, dentro de out, fuera inside, dentro

here, aquí there, allí right there: allí no más

over there: por allá near, cerca de above, sobre

below, debajo where, donde rather, bastante

for, para late, tarde early, temprano

ago, hace tiempo soon, pronto then, entonces

now, ahora also, también when, cuando

how, cómo very, muy often, a menudo

only, solamente too, demasiado almost, casi

little, poco well, bien ever, alguna vez

so, así yes, sí; no, no

quite, bastante still, todavía yet, aún



2. Derived Adverbs:

Manner Adverbs are formed, the most time, by adjectives or past participles plus sufixe "-ly"

proudly, from proud (orgulloso) richly, from rich (rico)

diligently, from diligent (aplicado) opposedly, from opposed (opuesto)

easily, from easy (fácil) prettily, from pretty (hermoso)

a. Adjectives finished in -ly (-mente) are used without modification as adverbs (early, monthly, biweekly, yearly);

b. Adjectives finished in -ll must add only -y (fully, de full);

c. Adjectives finished in "-ue" lose "e" (truly, de true);

d. Adjectives finished in -le change "-e" by "-y" (nobly, de noble).



3. Composed Adverbs:

a. They are made by a noun and an adjective:

halfway, a medio camino; likewise, del mismo modo;

meantime, mientras tanto; otherwise, de otro modo;

b. They are made by a preposition before a noun, a adjective or another adverb:

ashore, en tierra; afoot, en movimiento; along, adelante.

Along is used sometime with verbs of moviment in progressive tense when don't mention any destiny, and they are not translating in spanish language

Bring some friends along, trae algunos amigos; I was driving along, iba manejando.


COLOCATION

Adverbs are put:

1. next to verb, if it is alone:

He came quickly, vino rápidamente.

2. next to verb and it complement, but if it was short can put before it:

He took his hat off and put his coat on, se quitó el sombrero y se puso el abrigo.

3. Before an adjective:

Bill is very tall, Bill es muy alto.

4. If the verb is composed, adverbs are put between the auxiliary and the verb:

I have never been to Budapest, nunca he estado en Budapest.

5. Adverbs always, never, ever, sometimes, usually, seldom, often, scarcely, are put before the verb:

He never writes, nunca escribe.