极限若lim(X→1)f(x
若lim(X→1) f(x-1)/（x-1）=1,则lim(X→1) （X-1）/f(2-2X)= A.-1 B.1 .-1/2 D.1/2
选C: lim(X→1)( X-1）/f(2-2X) =lim(x->1) (-1/2)(2-2x)/f(2-2x) = (-1/2)lim(2x->2)(2-2x)/f(2-2x) =-1/2