Computers are useful machines. They can help people a lot in their life. For example, they can help people save much time, and they can help people do hard work. Today more and more families have computers. Parents buy computers for their children. They hope computers can help their children improve their studies. But many of the children use computers to play games, watch movies or chat, instead of studying. Many teachers and parents _ that computers make children fall behind. So many parents don't allow their children to play computers again. In some other countries, even some scientists hate computers. They say computers let some people lose their jobs or bring them a lot of trouble. Will computers really bring trouble to people or can they bring people happiness? It will be up to people themselves. In this passage we know computers  _  .
also bring us trouble bring us happiness only are hated by people are bad for people's health