@HelioCesar
Not bad, not bad... I see a few mistakes, but nothing seizure-inducing.
You seem to be having a bit of trouble with your indefinite articles, though.
Just in case you don't know what an "indefinite article" is, it's used to indicate nouns that are not specific - that is, generally indicating something that could be anything that noun can apply to. It's pretty easy to understand once you go through a few examples...
Indefinite: "I ate an apple."
Specific: "I ate that apple."
Indefinite: "I saw a car."
Specific: "I saw his car."
English has only two indefinite articles, "a" and "an", and which one you use is really pretty easy. If a noun has a vowel as the first letter, then you're supposed to use the indefinite article "an" instead of "a", even if it isn't pronounced as a long-vowel. Otherwise, nouns starting with consonant sounds get "a" as the indefinite article.
Examples:
"A car"
"An automobile"
"A door"
"An entrance"
"A lightbulb"
"An indicator"
"A piece of fruit"
"An orange"
"A parasol"
"An umbrella"
This also applies to any noun that starts with a "vowel sound", so this means that words like "hour" are used with "an" because the "h" is silent while the "o" is vocalized. This means it works for acronyms as well.
"A second"
"An hour"
"A light"
"An LED"
Try saying those nouns with the with an "a" instead, and you'll notice how it feels subtly awkward. This is because using only "a" means you have to apply a glottal stop with those nouns that start with a vowel sound. A glottal stop is a very brief pause in your vocalization and, in English, is
generally only done for a single word and not two words. Common examples in everyday use are words like "Ah-HAH!" or "Uh-oh!"
THERE IS AN EXCEPTION, THOUGH.
The long vowel sound for the letter "U", because the sound itself is actually a consonant sound.
"A unit"
"A European"
"An uncle"
"An undershirt"
Also, if there's an adjective, then go by that instead of the noun.
"A big apple"
"An ugly person"
Hope this helps.