美国中部大平原上的大河是 (      )

计算： $\sqrt{32}\times \sqrt{\frac{1}{2}}-{\left(\sqrt{3}-2\right)}^0-\left|-2\right|+2^{-1}$ ．

   Do you know the Chinese saying “He who doesn't reach the Great Wall is not a true man”? Mr. White knows it. Next month he is going to Beijing with his wife. They are going to visit the Great Wall. They are staying in Beijing for about a week. They have a lot of Chinese friends there, so they are visiting them. Then they're flying to West Lake in Hangzhou. They are going boating there and staying there for about three days. Mr. White knows that the Yellow Mountain is very famous in China. So they’re going to Anhui to go hiking in the great mountain. After two days in Anhui they'll have to go back to Sydney.
   “I'm taking lots of photos in China. When I get back to Sydney, I am going to show the photos to my friends. I want my friends to know more about China.” said Mr. White.

依次填入下面一段文字横线处的语句，衔接最恰当的一组是 (    )
我们游览到九龙溪的上游处下山，只见对面三十多米高的崖壁缝隙中，流出一支瀑布，
_____________,______________ ,______________ ,_______________ , 气势雄浑而磅礴，豪迈而坦荡。
①  溅着似玉如银的水珠
②  翻滚着白色的浪花
③  迸发出连续而不断的春雷般的轰鸣声
④ 闪烁着五彩缤纷的霞光

如图，DE是△ABC中AC边的垂直平分线，若AB=10厘米，AC=9厘米，BC=8厘米，则△EBC的周长等于（　　）