$g_{ij}(x)\in L^\infty(\mathbb{R}^n, M^{n\times n})$ is a metric in $\mathbb{R}^n$ satisfying $\lambda |x|^2\leq g_{ij}x^ix^j\leq \Lambda |x|^2$($\lambda>0$&$\Lambda>0$)
Can we find a Lipschitz homorphism $x=f(y)$ of $\mathbb{R}^n$ with $f(0)=0$, s.t. the new metric $h_{kl}(y)=g_{ij}(f(y))\frac{\partial f^i}{\partial y^k}\frac{\partial f^j}{\partial y^l}$ satisfying Gauss lemma, That is: $$h_{kl}(y)y^k=y^l$$