填空题 （共 6 题 ），请把答案直接填写在答题纸上
$I=\lim _{x \rightarrow 0} \frac{1}{x^2}\left\{\ln \left(1+2 x-x^2\right)-6\left[(1+x)^{\frac{1}{3}}-1\right]\right\}=$
$\lim _{x \rightarrow 0} \frac{\mathrm{e}^{x^2}-\mathrm{e}^{2-2 \cos x}}{\mathrm{e}^{x^4}-1}=$
$\lim _{x \rightarrow 0} \frac{\ln \left(\sin ^2 x+\mathrm{e}^x\right)-x}{\ln \left(\mathrm{e}^{2 x}-x^2\right)-2 x}=$
$\lim _{x \rightarrow 0} \frac{\left(\cos x-\mathrm{e}^{x^2}\right) \sin x^2}{\frac{x^2}{2}+1-\sqrt{1+x^2}}=$
$I=\lim _{x \rightarrow+\infty}\left(\sqrt[6]{x^6+x^5}-\sqrt[6]{x^6-x^5}\right)=$
$I=\lim _{x \rightarrow 0} \frac{(1-\sqrt{\cos x})(1-\sqrt[3]{\cos x}) \cdots(1-\sqrt[n]{\cos x})}{(1-\cos x)^{n-1}}=$