A:a=-1,b=1
B:a=-1,b=-1
C:a=1,b=-1
D:a=1,b=1
阅读课文《黔之驴》,完成各题。
Why not ____ your teacher for help when you can't finish _____ the story by yourself?
动物A最重要的特征是____,从而提高了后代的成活率.