A lift is very useful. It is a small room. It goes up  down all day. Sometimes a worker

    ( stand) in the lift. He or she operates(操作)it up and down. In modern lifts, there (be) no worker. People walk in. They know which floor they want to go. They push a button(按钮)and the lift goes to that floor.

    It's very fast and easy.   Lifts are very important to us. Why？ Think about a tall (build). Maybe it has twenty floors. Maybe it has fifty or (many). Who can walk up all the stairs(楼梯)？Maybe people can climb them once. Can someone climb thirty floors to an office every day？ Can small children walk up to their rooms on twenty-fourth floor？ Can their mothers fathers carry food up to all those stairs？Of course not. We can have very high buildings  we have lifts. We could not have all the beautiful tall buildings without lifts. Because it is too tired for people (climb) the stairs every day.