The H\"older continuity of a class of 3-dimension ultraparabolic   equations
  We obtained the $C^\alpha$ continuity for weak solutions of a class of ultraparabolic equations with measurable coefficients of the form $${\partial_t u} = \partial_x(a(x,y,t)\partial_x u) +b_0(x,y,t)\partial_x u+b(x,y,t)\partial_y u,$$ which generalized our recent results on KFP equations. 
Wendong Wang and Liqun Zhang