A:大鲵
B:蜥蜴
C:中华鳖
D:扬子鳄
— What do you usually do in the morning?
—I often practice_______English.
若关于x的方程 ax+1x-1﹣1=0无实根,则a的值为____ .
圆C1:x2+y2+4x+4y+4=0与圆C2:x2+y2﹣4x﹣2y﹣4=0公切线条数为( )
∫121x+xdx=( )