I wrote the following on a student’s essay (in Spanish) and decided to quote myself on my blog to preserve these ideas for humanity:
every language is a universe of its own. In order to speak a language, understand it and write well in it, it is not enough to pass through on a package tour that only allows you to see the exciting world of a language from the window of a bus. You have to become a citizen (or, at least, a permanent resident) of this strange and fascinating universe. You have to gain an understanding of the laws that govern it.
No language is exactly alike another language. It isn’t possible to find an exact, word-for-word rendering of any sentence or paragraph. If you write a sentence in English and then look up every single word in a Spanish dictionary, you will not end up with a meaningful sentence in Spanish. All you will create will be a sad jumble of meaningless words that refuse to comw together in a coherent whole.