$2)\mathop {\lim }\limits_{x \to 0}\frac{2\sin x-\sin 2x}{x^{3}}.$$3)\mathop {\lim }\limits_{x \to +\infty }\left ( x+2 \right )\sin \frac{2}{x}.$$4)\mathop {\lim }\limits_{x \to \frac{\pi }{2}}\left ( \frac{\pi }{2}-x \right )\tan x.$$5)\mathop {\lim }\limits_{x \to 0}\frac{\tan x-\sin x}{x^{3}}$