设函数f（x）=|x+ $\frac{8}{m}$ |+|x﹣2m|（m＞0）．

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．

城市人口迅速增加会产生（　　）

生物的性状是由____控制的．它是具有____效应的DNA片段．

      It was the first day of biology class. The teacher wanted to give a good1  to his class. He wanted to  2  his students’ eyes to the world of biology.
      He knew that 3  young students was not easy, so he worked 4  and tried to find a good way to teach this class.5  thinking for a long time, he made a 6  at last. He decided to show the kids something7 and teach them a lesson at the same time.
      He asked his students to 8  carefully. Then he began. He put a worm(虫子) into a glass of water. The worm 9 around in the water. Then he put a second worm into a glass full of alcohol(酒精). It died at once. He asked the students if anyone knew about 10 they learned from it. A boy said, “You showed us that if we drink alcohol we won't have worms.”