sentence1: this degenerate case of a decoupled evolution explains the fact that in newtonian and quasi-newtonian models backreaction has no or little relevance , q d vanishes .
sentence2: this degenerate case of a decoupled evolution explains the fact that in newtonian and quasi-newtonian models backreaction has no or little relevance and spatially flat , relativistic spherically symmetric dust solutions , q d vanishes .