(1/2+1/3)+(1/2^2+1/3^2)+......+(1/2^n+1/3^n)+......
= (1/2)/(1-1/2) + (1/3)/(1-1/3) = 1 + 1/2 = 3/2. 收敛。 选D
limnsin(1/n) = lim[sin(1/n)](1/n) = 1 ≠ 0, 发散。选B
。
