Passage Two Overhead bridges are found in many parts of Beijing, especially in places where traffic is very heavy and crossing the road is erous. The purpose of these bridges is to enable pedestrians (行人) to cross roads safely. Overhead bridges are used to very much the same way as zebra crossings. They are more efficient (效率高的) although less convenient because people have to climb up a long flight of steps. This is inconvenient especially to older people. When pedestrains use an overhead bridge, they do not hold up traffic. However, when they cross a busy road using a zebra crossing, traffic is held up. This is why the government has built many overhead bridges to help pedestrians and to keep traffic moving at the same time. The government of Beijing has spent a large amount of money on building these bridges. For their own safety, pedestrians should be encouraged to use them instead of risking (冒…危险) their lives by dashing across the road. Old people , however , may find it a little difficult climbing up and down the steps, but it is still much safer than walking across the road with all the er of moving traffic. Overhead bridges serve a very useful purpose. Pedestrians, both old and young, should make it a habit to use them. This will pr unnecessary accidents and loss of life. Which of the following statements is true according to the passage（）