题目内容
第二节 完型填空
阅读下面短文,从短文后所给各题的四个选项(A、B、C和D)中选出能填入相应空白处的最佳选项。
Why is space left between the rails of a railway line where one piece joins the next? The space 【B1】 to let the rail 【B2】 when it gets hot. On a hot day, the metal expands and if it 【B3】 to do this, the rails would bend 【B4】 shape. This caused railway 【B5】 in the past 【B6】 solids expand much less than liquids or gases, the 【B7】 increases can add up to a lot, when there are long.
【B8】 of rail. For example, the difference in length of rail, in summer and winter, 【B9】 the distance between London and Edinburgh, is about 1/4 mile.
We 【B10】 keep in our minds and must not forget the expansion of metal when we build a very long metal bridge 【B11】 . So spaces are left in the places 【B12】 the metal is joined.
When a solid gets colder, it becomes smaller in 【B13】 We can make use of the 【B14】 that solids expand when they 【B15】 , and become smaller in size then they 【B16】 colder.
For example, when an iron band has to fit tightly round a wooden wheel, first we make it 【B17】 than the wheel, then we 【B18】 it, so that it goes on 【B19】 . When it gets colder, it becomes smaller in size and 【B20】 the wheel very tightly.
【B1】
查看答案
搜索结果不匹配?点我反馈
更多问题