— What's ______?
— It's a tiger.
A:this
B:they
等差数列{an}中,a1+a9=10,a2=﹣1,则数列{an}的公差为( )
蜘蛛织网行为的叙述错误的是( )
已知向量a,b,c满足a=b=a·b=2,a-b·b-2c=0,则b-c的最小值为( )