As for virtual reality, concerned critics have warned that there could be dangers in this powerful new medium. Will we have VR games in which people can commit virtual crimes（犯罪）? After people get used to VR, will they want to return to reality? Will we forget how to live and work with real people? On the other hand, some people think that VR will help us improve the world. By experimenting harmlessly inside a VR world, we will be able to see the dangers we may face in the future. Then we will be able to avoid them in real life.