阅读材料，回答下列问题。

材料一：贞观、显庆年间，唐朝曾三次派王玄策出访印度。除了官方的使节往来外，民间自发的商贸、文化交流活动也极为频繁，李勉做广州刺史时，广州每年来华的外国商人，至少也在80万以上。

——选自《中国文化通史》隋唐五代卷

材料二：南宋时，海外贸易发达，商船远达阿拉伯半岛和非洲东海岸。在航海中广泛使用了我国古代四大发明中的某一项成就。

材料三：“明初，社会安定，国力雄厚。1405—1433年，明政府先后七次派郑和下西洋。……郑和远航将中国的丝织品、瓷器、茶叶、印花布、铁器等货物销往各国，载回东南亚地区的香料、染料、药物及大量供皇室贵族享有的珍珠、玛瑙、宝石、象牙等奢侈品。”

——北师大版初中历史教材

材料四：乾隆二十二年（1757年），清政府规定广州是允许外商来华贸易的唯一口岸，而且即使在广州也百般限制中国人与外商接触。政府特许的“十三行”不仅垄断了与外商的经济往来，还代政府出面办理交涉事宜。

乙酸乙酯（C₄H₈O₂）常用作食品、饮料的调香剂．下列有关乙酸乙酯的叙述正确的是（　　）

    One day an American called Simon went to London to visit his friend, Rick. Rick told him that his flat was on the first floor. When he arrived, Simon went straight to the first floor of the building. But he was told that there was no Rick on that floor. Do you know why?

    In fact, the British call the first floor of a building the ground floor. The floor above the ground floor is the first floor, while Americans would call it the second floor.

    The story shows that there are a few culture differences between Britain and America, though the British and Americans both speak English.

    The British usually hide their feelings. They seldom start a conversation with strangers. For example, on the train the British often spend their time reading newspapers or books. But Americans are quite different. They're more active and easier to talk with.

    The British and Americans may use different terms for many things. The British usually use “football”, “eraser” and “mail” while Americans prefer to use “soccer”, “rubber” and “post”.