题目

Dog walkers provide a 20 to 60-minute daily walk for a client’s（客户）dog, making sure the dog answers the call of nature and gets proper exercise. They often walk more than one dog at a time. Some walkers work for dog-walking services, especially when starting out. Others have their own businesses, and build by word of mouth and advertising. Dog walkers often work part-time, and some provide other services like pet sitting or transporting. In N.Y.C., dog walkers usually earn about $25 an hour. If you work for a dog-walking business, you may earn less-if you are on your own dealing with6．说明函数y=-（x+1）（x-3）的图象的变化情况：在对称轴x=1的左侧的部分是上升的，右侧的部分是下降的．