Lika, I will respond to your comment here, where there is more room to write than in the tiny "comment" box.
1. Usually, the definite article "the" may be used when the noun it modifies is known, specified, or, as you say, "concrete." Example: "Russia is the largest country in the world." We use "the" because there is only one particular country -- Russia -- which fits the description of the largest in the world. However, in your paragraph, the country was not known, specified, or concrete. There are many countries where the native language is English. No one reading your paragraph could know which English-speaking country you had in mind or were referring to. So I used the indefinite article "a", which is used to modify a non-specific or non-particular noun.
2. You are probably referring to a so-called rule that the word "any" is only used in questions and negative sentences. However, that rule is not absolute. Please see this webpage: http://eslonthehill.wordpress.com/2009/09/29/grammar-question-2-of-the-week-any-affirmative-sentences/
Please pay special attention the paragraph that begins by mentioning the COBUILD English Grammar. There it is explained that "any" may be used in sentences which refer to something that may or not exist. One of the examples given there is, "Check if you’re in any doubt." This is similar to my suggested sentence, "Please, correct my post if I made any mistakes." That sentence refers to something (mistakes) which may or may not exist, and therefore the use of the word "any" is appropriate.
