在历史发展的长河中，民族团结和国家统一成为主流，更成为国家繁荣富强的重要基础。

材料一：拉萨市大昭寺前的广场上矗立着建立于公元823年的“唐蕃会盟碑”，这是汉藏两民族团结友好的历史见证。拉萨市西藏人民会堂前的广场上的“民族团结宝鼎”(青铜器)在阳光下熠熠生辉，这是2001年中央政府为庆祝西藏和平解放50周年向西藏自治区赠送的，表现的是民族团结、发展进步的主题。

材料二：唐太宗：“自古皆贵中华，贱夷狄，朕独爱之如一。”

——《资治通鉴》

材料三：大宋皇帝谨致誓书于大契丹皇帝：……以风土之宜，助军旅之费，每岁以绢二十万匹，银一十万两……

材料四：宋与周边少数民族政权之间战争频繁，屡战不胜，和辽、西夏、金议和。这使得宋和其他少数民族政权之间保持了长时间的友好交往。

请回答：

关于物体在液体中受到的浮力，下列说法正确的是（   ）

 有一种“超声波喷雾降温扇”．在风扇转动时还可以喷出水雾．喷雾可以增加空气中的水分，风扇吹风加快了空气中水分的____，就加快了从周围物体____热量，从而达到降温的目的．

    China has once again showed its ability to change the world with its “new four great ____(invent)”—high-speed rail, electronic payment, shared bicycle, and online shopping

    China's new-generation high-speed train, the Fuxing, is now one of the ____(fast) trains in the world, which can travel at a speed of 350 km/h. Besides high-speed rail, China ____(improve) people's lives in many other innovative (创新的) ways over the last decade.

    Bike sharing, for example, is not new itself. But China has made ____much more convenient and popular both in China ____overseas. Leading Chinese bike-sharing companies Mobike and Ofo are now operating in foreign countries such as Singapore and Britain.

    And back in China, when riding a shared bike, you can stop ____ (buy) and eat whatever you want ____(simple) with a tap of your phone. You could easily pay with your smartphone by ____(scan) the seller's QR code. Cashless payment has grown into a____(choose)for Chinese  people—even a pancake seller is using Alipay.

    Besides, the four innovative ways of life are most appealing ____youths from 20 countries participating in the Belt and Road innovation, and they wish their countries would emulate(仿效) China in terms of technological achievement

对于哥伦布及其事业的评价，现在更多的人认为，不能站在当时印第安人的立场上，也不能仅从对西欧某些国家资本主义利弊得失的角度出发，应将其置于“世界大探险时代”和人类历史长河中进行宏观考查。对以上材料分析正确的是（    ）