  The exceptional infinite-dimensional linearly compact simple Lie superalgebra
${E}(5,10)$, which Kac believes, is the algebra of symmetries of the ${SU}_{5}$
Grand Unified Model. In this paper, we give a proof of Kac and Rudakov's
conjecture about the classification of all the degenerate generalized Verma
module over ${E}(5,10)$. Also, we work out all the nontrivial singular vectors
degree by degree. It is a potential that the representation theory of
${E}(5,10)$ will shed new light on various features of the the ${SU}_{5}$ Grand
unified model.
