A group of frogs were traveling through the forest, but unluckily two of ____fell into a hole. The other frogs tried to help them. When they saw how____ the hole was, they cried to the two frogs that they could not be saved. The two frogs didn't care and tried their____to jump up out of the hole. The other frogs kept saying that they were sure to die. Finally, one of the two frogs heard____the other frogs were saying and gave up. Then he fell ____and died.

    However, the other frog continued to jump as hard as he could____last, he made it out. When he got out, the other frogs asked, "Did you hear us?" The frog, who had a____hearing, explained, "I thought you were encouraging me ____ the time."

    The story teaches us a ____ There is power of life and death in the tongue(言语）.An encouraging word to those who are down can help them out ____a discouraging word can kill them.

讨论函数$f\left(x\right)$极值点的个数，并说明理由；

偶函数f(x)在0,+$\infty$)上为增函数，若不等式$f(ax-1)<f(2-x^2)$对$x\in R$恒成立，则实数a的取值范围为(   )