lim_(n to infty)((1)/(n^2)+(2)/(n^2)+...+(n)/(n^2))=().A. lim_(n to infty)(1)/(n^2)+lim_(n to infty)(2)/(n^2)+...+lim_(n to infty)(n)/(n^2)=0+0+...+0=0B. lim_(n to infty)(1+2+...+n)/(n^2)=inftyC. lim_(n to infty)((1+n)n)/(2n^2)=(1)/(2)D. 极限不存在

$\lim_{n \to \infty}(\frac{1}{n^{2}}+\frac{2}{n^{2}}+\cdots+\frac{n}{n^{2}})=()$.

A. $\lim_{n \to \infty}\frac{1}{n^{2}}+\lim_{n \to \infty}\frac{2}{n^{2}}+\cdots+\lim_{n \to \infty}\frac{n}{n^{2}}=0+0+\cdots+0=0$

B. $\lim_{n \to \infty}\frac{1+2+\cdots+n}{n^{2}}=\infty$

C. $\lim_{n \to \infty}\frac{(1+n)n}{2n^{2}}=\frac{1}{2}$

D. 极限不存在