An abelian torsion group is an abelian group in which each element has finite order, i.e. there is an integer $n$ such that $g^n=1$ for all $g\in G$. Since this is related to a theorem by Engeler, Ryll-NardzewskiI and Svenonius that a theory with only finitely many types is $\aleph_0$-categorical, the theory of abelian torsion group should be $\aleph_0$-categorical. I'd like to know how to prove it.