What do you usually do to get pocket money from your parents? In western countries, many children do chores to get pocket money. They usually start to do this at 10 years old.
School students have to do homework and study for tests. They don't have a lot of free time in the week. They often do chores at the weekend.
Young kids only do easy chores. So they don't get much money. But that's all right. Many of them only want to buy candy. And candy is cheap! They help wash up after dinner and feed the family cat or dog.
When they get older, kids want to buy more and more things. They want things that are more expensive than candy. Then they have to work harder! They often wash the family car, cut the grass, walk the dog and cook dinner.
Some jobs are a good way for kids to learn new things. For example, they can learn to use a lawnmower(割草机) or how to cook. Of course, their parents help them at first.
则实数a的取值范围