Once there was an island where all the feelings lived: Happiness, Sadness, Knowledge, and all of the others, including Love. One day it was said that the island would go down, so all made boats and left except Love.
Love was the only one who stayed. Love wanted to offer her help until the last possible moment. When the island had almost gone down, Love decided to ask for help.
      Richness was passing by Love in a great boat. Love said, “Richness, can you take me with you?” Richness answered, “No, I can't. There is a lot of gold and silver in my boat. There is no place here for you.”
       Sadness was close by, so Love asked, “Sadness, let me go with you .” “Oh, Love, I am so sad that I need to be by myself!”
Happiness passed by Love, too, but she was so happy that she did not even notice when Love called her.
Suddenly, there was a voice, “Come, Love, I will take you.” It was an elder. Love was so excited that she even forgot to ask who the elder was. So Love asked Knowledge, another elder, “Who helped me?” “It was Time,” Knowledge answered. “Time?” asked Love. “But why did Time help me?”
      Knowledge smiled with deep wisdom and answered, “Because only Time understands how valuable Love is.”

函数$f\left(x\right)=\frac{ax+b}{1+x^2}$是定义在（﹣1，1）上的奇函数，且$f\left(\frac{1}{2}\right)=\frac{2}{5}$．

（1）确定函数的解析式；

（2）证明函数f（x）在（﹣1，1）上是增函数；

（3）解不等式f（t﹣1）+f（t）＜0．

以前许多农村家庭用煤球煮饭，现在改用煤做成蜂窝状，这种变化是为了____ ．

A、防止温室效应的产生                    B、增大煤与空气的接触面积

C、降低煤的着火点                        D、____ ．

已知二元一次方程2x﹣y=1，用y的代数式表示x为____．