因为x^2-x-1=0,所以x^2=x+1,
那么-x^3+2x^2+2007
=-x^2*x+2x^2+2007
=-x(x+1)+2(x+1)+2007
=-x^2-x+2x+2+2007
=-x-1-x+2x+2+2007
=2008