﹣$\frac{1}{2}$​的绝对值是（　　）

世界经历了从相互隔绝到全球化发展的过程。阅读下列材料，回答问题。

材料一：2013年******提出建设“新丝绸之路经济带”和“21世纪海上丝绸之路”的战略构想。这让我们想起了中国古代的对外交往历史悠久，源远流长。从汉代丝绸之路的开辟到前期的对外友好交流，我国为世界经济的发展作出了杰出贡献。

材料二：公元1500年前后的地理大发现，拉开了不同国家相互对话和相互竞争的历史大幕，由此，大国崛起的道路有了全球坐标——正是从那个时候起，割裂的世界开始连接在一起，经由地理大发现而引发的国家竞争，拉开了不同文明间的相互联系、相互注视，同时也拉开了相互对抗和争斗的历史大幕。

——《大国崛起》解说词

材料三：科技的发明便利了人们之间的交流，缩短了空间距离。下列这些发明分属于三次科技革命，请按要求归类。

材料四：美国苹果手机有450多个零部件，苹果公司在全球有数百家供应商，分布在中国内地、中国台湾、新加坡、泰国、马来西亚、捷克以及美国等地，但大部分产品在中国组装。

请回答：

   Imagine one day the water taps (水龙头) in your house stop running. You have to pay a lot of money to buy water from shops. And still there isn't enough water for everyone. Your mother has to save the family's shower water to use for washing clothes. Would you be able to stand that kind of life?
   Probably not. But that is what kids in Yemen (也门) are experiencing (经历). According to a report, the capital, Sana, will run out of drinking water as early as 2025.
   Because of the water shortage (短缺), the Yemen government often cuts the water supply (供应). Hannan, an 18-year-girl, tells the Teens, “In a good week we'll have a water supply all week. But then the next week there will be water only for a day or two.”
   Hannan says only rich people have enough water to use. They can buy water from the shops or from the water trucks. Private (私人的) companies own the trucks, They travel around the city every day to sell water-- at very high prices.
   “A lot of people can't pay for it,” she says.
   The government is thinking of making use of seawater. But it will cost a lot and it may not happen soon enough to help the people of Yemen.

8＋7=____

11－8=____

12－6=____