  In this note, we will show that if a measured Gromov-Hausdorff limit space of
a sequence of Riemannian manifolds with lower Ricci curvature bound has dense
2-regular set, then it is homeomorphic to a 2-dimensional manifold in an open
full measure set. This result gives a positive answer to an open problem in
[Naber, Open problem 3.4] in dimension 2 and for dimension larger than 2 there
are counterexamples by [HNW, Zhou].
