  The main aim of this paper is to present a direct proof of Di Nola's
representation Theorem for MV-algebras and to extend his results to the
restriction of the standard MV-algebra on rational numbers. The results are
based on a direct proof of the theorem which says that any finite partial
subalgebra of a linearly ordered MV-algebra can be embedded into $\mathbb Q\cap
[0,1].$
