生活在长江流域、属于我国最稀少的濒危动物的是( )
A:扬子鳄
B:中华鲟
C:白鳍豚
D:娃娃鱼
—He is ________ and I don't think he'll help us with anything.
偶函数f(x)在0,+∞)上为增函数,若不等式f(ax-1)<f(2-x2)对x∈R恒成立,则实数a的取值范围为( )