1. Wrong question (so-called high-order derivatives are generally only derivatives of second order and above, and there is no satisfactory answer)

2. Choose B for vertical asymptote x=1 and y=1, C.

3. Discontinuity is nondifferentiable, and of course it is not derivable. Choose A, C.

4. Choose B.

7.lim< x-> ∞> [2x/(1+x? ) ]=1, choose A.

8. It is a sufficient condition, choose A, B, C and D

9. Choose A, B, C and D

11, choose C and D. 。