The Big Ben is very famous throughout the world, but nobody really knows the reason why it is called Big Ben. However, there are two stories may explain the reason. Some people say that it was __1__ named Benjamin Caunt, a boxer, who was called Big Ben. __2__ More people believe the name comes from a Welshman,Sir Benjamin Hall. __3__ He commissioned the work in 1859. A story arose that, during a debate in House of Commons on what to call the bell, Sir Benjamin was about __4__ to give his ideas that someone who sat behind the front bench shouted, __5__ "Let's call it Big Ben!"
The history of the bell tower, since the beginning of its design, is by no means smooth, however. Due to disagreements about the clock's design, it takes fifteen years to build. In 1857, the structure was __6__completed and tested on the ground, but a four-foot crack appeared,and the bell had to cast again. Finally, the clock started ticking __7__ on May 31,1859, and stroke its first chime on July 11. Then, in __8__ September, the bell cracked again. It was silent for four years but was eventually turned a quarter of a revolution. As a result,the crack was not under the striking hammer. Craftsmen made a square above the crack to stop it to cracking further and it can __9__ still be seen today.The Big Ben is famous not only for its thirteen-ton weight, but also for its accuracy, that is a result of its presise mechanism. __10__ Even one extra penny's weight on the balance would cause a gain of two fifths of a second in twenty hours. Although there have been several problems, the bell still chimes today.
答案：
1.^may--that/which。two stories 后面添加that/which。此处缺少关系代词，关系代词作may explain the reason的主语不能省略。
2.named^--after。根据上下文意思，这里是说大本钟是根据一个拳击手GenjaminCaunt的名字命名的，所以用固定搭配be named after。
3.comes--came。根据上下文的时态综合看来，这里是说过去的情况，所以要用一般过去时。
4.^House--the。House of Commoms是专有名词，前面需要定冠词。
5.that--when。根据上下文意思，此处是说当Sir Benjamin正要书哦自己的看法时，坐着第一排座位后面的某个人喊道：“我们就叫它大本钟好了。”事实上，此处句中的was about to已经给了我们提示，让人不禁想到be about to do sth.when 的习惯用法。
6.takes--took。这里还是时态上前后一致的问题。
7.^cast--be。此处需要的是被动态，“大本钟不得不被再次浇铸”
8.stroke--struck。此处的意思是大本钟“敲响”了，struck是原型动词strike的过去式，而stroke是动词原形，意思是“抚摸，轻抚”。
9.to--from。这里需要的意思是“阻止……的发生”，所以用固定搭配“stop...from doing...”
10.that--which。此处是非限定性定语从句，that不可以使用，要用关系代词which。
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