2-DIMENSIONAL BLACK-HOLE AND SINGULARITIES OF CY MANIFOLDS

We study the degenerating limits of superconformal theories for compac tifications on singular K3 and Calabi-Yau threefolds. We find that in both cases the degeneration involves creating an Euclidean two-dimensi onal black hole coupled weakly to the rest of the system. Moreover we find that the conformal theory of A(n) singularities of K3 are the sam e as that of the symmetric fivebrane. We also find intriguing connecti ons between ADE (1,n) non-critical strings and singular limits of supe rconformal theories on the corresponding ALE space.