题目

写一写木头的用途We get wood from trees．We use wood to make many things．We use wood to make ( ) ． We use wood to make ( ) ． We use wood ( ) ． 答案：The usage of wood Wood is very important to our life. We get wood from trees．We use wood to make many things．We use wood to makedesks.We use wood to makepencils and paper.Wood is very useful. Let's plant more trees! And wo can get much wood.函数f（x）的定义域为D={x|x≠0}，且满足对于任意x1、x2∈D，有f=f（x1）+f（x2）（1）求f（-1）的值；（2）判断f（x）的奇偶性并证明；（3）如果f（）=1，且f（x）在（0，+∞）上是增函数，若f（x+5）+f（x）≥2，求x的取值范围．