阅读理解。 London's River Thames has twenty-seven bridges. But Tower Bridge, the first bridge over the Thames as you travel to London from the sea,is the most famous of them all. What makes Tower Bridge so exciting? Why do visitors come from all over the world to see it? The thing that is surprising about Tower Bridge is that it is open in the middle. It does this to let the big ships through to the Pool of London.lf you are lucky enough to see the bridge with its two opening arms high in the air,you will never forget it. On its north side stands the Tower of London it self.Although they look the same age,the Tower is almost a thousand years old,and Tower bridge is only about one hundred, It was built in the 1890s. By1850, everyone agreed that a bridge across the Thames near the Tower was most necessary. But the designers argued about the new bridge for another  thirty years.This took so long because they had two big problems. l. Tower Bridge is ______ . A. about one thousand years old B. the oldest and the most famous bridge in London C. the first one you can see when you go from the sea to London D. the one that took workers about 30 years to build 2. The Tower of London is ______. A. across from the Thames B. on the north of Tower Bridge C. in the middle of Tower Bridge D. much younger than Tower Bridge 3.Which of the following is NOT true according to the passage? A. You can see the bridge with its two opening arms high in the air at anytime. B. By 1850 everybody thought it most necessary to have a bridge built across the Thames near the Tower. C. It took the designers thirty years to argue about the bridge before it was built. D. It was no easy thing to build a bridge near the Tower. 4. Why is the bridge open in the middle? A. To make it special. B. To attract (吸引) more people from the world to see it. C. To let the big ship through to the Pool of London. D. BeCduse it is so long that has to be divided into two parts. 5. How long was the Tower Bridge built? A. A thousand years. B. A hundred years. C. Five thousand years. D. Five hundred years.