(3)下列命题中正确的是 ()-|||-(A)若 lim _(narrow infty )(u)_(n)=0, 则 sum _(n=1)^infty (n)_(n) 收敛-|||-(B)若 lim _(narrow infty )((u)_(n+1)-(u)_(n))=0, 则 sum _(n=1)^infty (u)_(n) 收敛-|||-(C)若 sum _(n=1)^infty (u)_(n) 收敛,则 lim _(narrow infty )(u)_(n)=0-|||-(D)若 sum _(n=1)^infty (u)_(n) 发散,则 lim _(narrow infty )(u)_(n)neq 0