Questions in fun-lim

Select	Question
	$\underset{n\to \infty }{\mathop{\lim }}\,\frac{\sqrt{n}}{\sqrt{n}+\sqrt{n+1}}=$
	$\underset{x\to a}{\mathop{\lim }}\,\frac{\sqrt{3x-a}-\sqrt{x+a}}{x-a}=$
	If $f(x) = \begin{cases} \,\,\,\,\,\,\,x,\;{\rm{when }}0 \le x \le 1\\ 2 - x,\;{\rm{when }}1 < x \le 2 \end{cases}$, then $\underset{x\to 1}{\mathop{\lim }}\,f(x)=$
	$\underset{x\to 1}{\mathop{\lim }}\,\frac{\log x}{x-1}=$
	If $\underset{x\to 2}{\mathop{\lim }}\,\frac{{{x}^{n}}-{{2}^{n}}}{x-2}=80$ , where n is a positive integer, then $n=$
	$\underset{x\to 0}{\mathop{\lim }}\,\frac{1-\cos 2x}{x}=$
	$\underset{x\to \infty }{\mathop{\lim }}\,{{\left( 1+\frac{2}{x} \right)}^{x}}=$
	$\underset{x\to 1}{\mathop{\lim }}\,\frac{(2x-3)(\sqrt{x}-1)}{2{{x}^{2}}+x-3}=$
	If $\underset{x\to 0}{\mathop{\lim }}\,kx\,\text{cosec}\,x=\underset{x\to 0}{\mathop{\lim }}\,x\,\text{cosec}\ kx$ , then $k=$
	$\underset{x\to 0}{\mathop{\lim }}\,\frac{{{e}^{1/x}}-1}{{{e}^{1/x}}+1}=$