  A class of backward doubly stochastic differential equations (BDSDEs in
short) with continuous coefficients is studied. We give the comparison
theorems, the existence of the maximal solution and the structure of solutions
for BDSDEs with continuous coefficients. A Kneser-type theorem for BDSDEs is
obtained. We show that there is either unique or uncountable solutions for this
kind of BDSDEs.
