题目

    When I was nine years old, I loved to go fishing with my dad. But the only thing that wasn’t very fun about it was that he could catch many fish while I couldn’t catch anything. I usually got pretty upset and kept asking him why. He always answered, ”Son, if you want to catch a fish, you have to think like a fish.” I remember being even more upset then because, “I’m not a fish!” I didn’t know how to think like a fish. Besides, I reasoned, how could what I think influence what a fish does? As I got a little older I began to understand what my dad really meant. So,(1），  则     （4分）  （2）由（1）知，则  ①当时，，令或 ， 在上的值域为                              （7分） ② 当时，      a.若,则                          b.若,则在上是单调减的   在上的值域为                           c.若则在上是单调增的   在上的值域为                         （9分） 综上所述，当时，在的值域为                        当时，在的值域为                  （10分）          当时，若时，在的值域为 若时，在的值域为 （12分） 即  当时，在的值域为 当时，在的值域为 当时，在的值域为