We can see walls everywhere in the world. But the Great Wall of China is the biggest of all. The Chinese call it. “The Ten-thousand-Li. Great Wall.” It’s in fact (事实) more than 6,000 kilometers long. It’s 4-5 meters wide. In most places, five houses or ten men can walk side by side. When you visit the Great Wall, you can’t help wondering (疑惑) how the Chinese people were able to build (建造) such a great wall thousands of years ago. Without any modern machine (机器), it was really very difficult to build it. They had to do all the work by hand. It took millions of men hundreds of years to build it.
   The Great Wall has a history of over two thousand years. The kings began to build the first parts of it around two thousand seven hundred years ago. Then, Qin Shihuang had all the walls joined up (连起来). He thought that could keep the enemy (敌人) out of the country.
Today the Great Wall has become a place of interest. Not only Chinese people but also people from all over the world come to visit it.

澳大利亚全国最大的工业城市和海港是（　　）

的主要成分是甲烷，此外还含有少量的乙烷、丙烷、二氧化碳、一氧化碳等。

材料一：（苏联斯大林时期）为了在尽可能短的时间内高速度实现工业化、农业就不能按常规发展，而是必须适应工业的要求，为工业化提供资金来源。

——《世界通吏》第三编

材料二：1953—1957年，全国工业建设项目达1万多个，我国过去所没有的一些工业部门，包括飞机制造业、汽车制造业、重型和精密机器制造业以及高级合金钢企业等，从无到有建设起来．

——摘自岳麓版《中国历史》（八年级下册》

材料三：1960年与1957年相比，（我国）工业总产值增长1.3倍，而农业总产值却下降了22.7%；工业和农业产值比例由5.7：4.3，变为7.8：2.2。

——摘自岳麓版《中国历史教学参考书》（八年级下册）