如图，某校数学兴趣小组为测得校园里旗杆AB的高度，在操场的平地上选择一点C，测得旗杆顶端A的仰角为30°，再向旗杆的方向前进16米，到达点D处（C、D、B三点在同一直线上），又测得旗杆顶端A的仰角为45°，请计算旗杆AB的高度（结果保留根号）

   A small town named Bundanoon in Australia has decided to stop the sale of bottled water(瓶装水). They say that bottled water can cause environmental problems. Too many resources(资源) are used to make bottled water. When people finish drinking the water, the bottles will be thrown away and go into dustbins. So they require local people in the town to stop buying bottled water and use tap water to drink. Visitors are encouraged to get water from water stations in the main streets, and fill the water in bottles that can be used again. The decision has been supported(支持) by all the shopkeepers in the town. Bundanoon is the world’s first town that has got its shop selling bottled water. Probably we should follow the example. Let’s stop buying bottled water and use tap water！

距离南极洲最近的大洲是（　　）