题目

硫酸亚铁（FeSO4）是常见补铁类保健品中的有效成分之一，其中铁、硫、氧三种元素的质量比为__________ ；铁元素的质量分数为_____（计算结果保留至0.1%）。 答案：7:4:8      36.8%A lift is wonderful. It is really only a small room. Rooms usually stay in one place. Lifts travel up and down all day long. Sometimes a worker stands in the lift. He or she operates it up and down. In modern lifts there is no worker. The people walk in. They know what floor they want. They push a button and the lift goes to that floor. It is all very fast and easy. Lifts are very important to us. Why? Think about a tall building. Maybe it has twenty floors. Maybe it has fifty or more. Who can walk up all the stairs? Maybe people can climb them one time. Can someone climb thirty floors to an office every day? Can small children walk up to their room on the twenty-fourth floor? Can their mother and father carry food up all those stairs? Of course not. We can have high buildings because we have lifts. We could not have all the beautiful tall buildings in the world without lifts. They are really wonderful.【小题1】Which of the following is true?A．A modern lift has no buttons.B．A modern lift has a worker to operate it.C．A modern lift can go up and down with no worker in it.D．A modern lift knows what floor people want.【小题2】If you want to go to the floor you want, you_______.A．ask for helpB．open the door of the liftC．ring the bellD．push the right button【小题3】Why do people have to use lifts? Because________.A．they have tall buildings B．they can't walk up and downC．old people and children need them D．lifts are wonderful