6、re are twenty seven bridges over the River Thames. And the Tower Bridge is thefirst bridge you have to pass if you go to London from the sea. It is close to the Towerof London, from which it got its name. It is a symbol (象征) of London.The Tower Bridge w
7、as set up over the River Thames in London in 1894 and is one ofthe finest and most famous bridges in the world. It is the only bridge over the Thamesthat can be raised and opened in the middle. The middle part can be raised to let thehuge ships pass. It
8、 used to be raised about 50 times a day, but now it is raised only 4 to5 times aweek. If you are lucky enough to see the bridge with its two arms open highin the air, you will never forget it.The Tower Bridge stands just on the s