Have fun in English!

Dear children! Congratulations, we have finished this lesson successfully! I want to thank you all your work and effort and, as a reward, this post is just for you to enjoy. And as usual, it's a challenge, in English language of course. In the document you must download here you will find a seven words sentence, but it's not written with letters, it's written with numbers! So, what you have to do is to guess the correspondance between numbers and letters, and then you will be able to construct the whole sentence. I'll give you some clues:
The first clue is: how clever are you?
And to make it a little easier, I provide you below the correspondance between some key letters and numbers.
 

21: A

1: I

25: R

8: L

23: V

Enjoy and... good luck!