1.lim n[ln(n-1)-lnn]=lim ln[(n-1)/n]ⁿ=lim ln(1- 1/n)ⁿ=lim ln{[1+ 1/(-n)]⁻ⁿ}⁻¹=ln(e)⁻¹=-1选A2.lim[x²/(x+1)-ax-b]=lim[(x²-ax²-ax-bx-b)/(x+1)]=lim[(1-a)x²-(a+b)x -b]/(x+1)=lim[(1-a)x -b/(x+1) -(a+b)]极限等于0,则1-a=0,a+b=0解得a=1,b=-1选C