语法填空
    That Beijing together with Zhangjiakou succeeded in getting the chance ____(host) the 2022 Winter Olympic Games, speeds up the development of Zhangjiakou City. Word came____the Beijing -- Zhangjiakou high-speed railway ,____ (locate) in North China, is currently under construction and ____(expect) to be completed by 2020 in preparation for the cities to host the 2022 Winter Olympics.
    ____, the project is a big challenge line, with ten stations situated along its route, starting from Beijing North Railway Station, heading west through the Great Wall, three times the____(long)of the capital's territory. Having a ____(totally) investment of 31.17 billion yuan , the trip between the two cities will only take 40 minutes, with the train____(travel) at an average of 250km/h. According to the plan, the high-speed railway will build two branch lines-- one is to Yanqing Station and____other to Taizicheng of Chongli,____the Olympic village lies. The full railway, which includes 72–kolometers section through Beijing , will be completed in four and a half years.

$\frac{x}{1.7}=\frac{7}{51}$

X=____

含20.0g NaOH的稀溶液与稀硝酸完全反应时，放出28.7kJ的热量，表示该反应的热化学方程式正确的是（　　）

下图是某地区人口年龄结构组成图，图中a、b、c分别表示1940年、1970年和2008年的人口年龄结构比重状况。读图回答问题。

从图中可以看出，这个地区人口变化趋势的特征有

下图为地中海沿岸某地地质构造与水循环示意图，读图完成下列各题。