Londons river Thames has twenty-seven bridges. Tower Bridge, the first bridge over the Tha

mes as you travel towards London from the sea, is the【C1】______of them all. The thing that is surprising about【C2】______is that it opens in the middle. It does this to let the big ships【C3】______to the Pool of London. If you are【C4】______enough to see the bridge with its two opening arms high in the air, you will never forget it. Tower Bridge is less than one hundred years old. It was built in the【C5】______. By 1850, everyone【C6】______that a bridge across the Thames near the Tower London which is almost a thousand years old was most necessary. But the【C7】______argued about the new bridge for about another thirty years. The argue lasted【C8】______long because of two problems. The new bridge must look like the Tower of London—everyone said so. It【C9】______not look like a modern bridge. But because of the tall ships it was【C10】______to have a modern design. At last, two【C11】______designers had the idea of an opening bridge. And they made it look like the Tower, so everyone was【C12】______. It was a wonderful success. There was so much traffic on the river【C13】______the bridge opened at least twelve times a day. A hundred years【C14】______, the River Thames was Londons busiest road. Today big【C15】______dont come so far up the Thames. Tower Bridge opens perhaps only twice a week,【C16】______the same wonderful machinery is still working. It can still lift the two【C17】______opening arms—each 1000 tons—leaving seventy meters for the ships to【C18】______. And they can still open and close the【C19】______in one-and-a-half minutes. Things are changing now at Tower Bridge, but whatever【C20】______in its exciting future, Tower Bridge will always mean London.

【C1】

A．widest

B．highest

C．newest

D．most famous