Every day there is less and less space on the Earth for rubbish. Yet every day we make more and more rubbish. What can we do? We can recycle some of our rubbish. Recycling means that the rubbish will be made into something that can be used again.

Recycling helps Earth. And it saves space in rubbish dumps. Half of everything that we put into landfills could be recycled instead. In fact, most things made of paper, metal, glass and plastic can be recycled.

Paper can be broken into small pieces and made into new paper. Steel and aluminum cans(金属罐)can be melted down(熔化)and made into new cans. The same is true of glass bottles. This can be done over and over again. Recycling doesn’t take as much energy as making these things the first time. So we can use less of Earth’s fuel resources.

Plastic can be melted down, too. Then it can be formed into park benches, playgrounds and so on. Some people call plastic the “wood” of the future. Things made of plastic will last about 400 years—even if they stay outside in the weather. No wood can do that!

Artificial intelligence (AI) is technology that lets machines do things that need “thinking.” It is a hard term to define (下定义) because AI isn’t actually one thing. Rather it’s a group of technologies that help machines get, understand and use information to perform tasks. The range of technologies is one of the reasons people use so many different terms to describe AI. In addition to artificial intelligence, terms like machine learning, cognitive computing and deep learning are common.

No matter which term is used, recent developments have received a lot of public attention. Some have welcomed the technology because of things that AI makes possible. For example, AI will have a big effect on areas like medicine and engineering. But the public attention has also produced a lot of fear and caution. In particular, many are concerned about the effects AI could have on people’s jobs.

According to a recent study, nearly five percent of jobs will disappear because of AI. High on the list are jobs in the producing and mining industries, where systems powered by AI are already performing tasks that people used to do, such as assembling (组装) cars, digging tunnels and loading materials. In the future, self-driving cars and trucks that depend on AI will also steal jobs for drivers. Moreover, AI systems will do many tasks now performed by legal assistants and accountants.

On the other hand, AI will also create many new jobs. More people will be needed to write software for AI systems as well as to set up and operate them. Meanwhile, jobs that require emotional intelligence, excellent communication skills and interaction with people will not be replaced by Al. These include jobs in fields like teaching, nursing, hairdressing and personal training.