如图分别为细胞结构和显微镜结构示意图，据图回答下列问题．
如图，在一次数学课外实践活动中，小聪在距离旗杆10m的A处测得旗杆顶端B的仰角为60°，测角仪高AD为1m，则旗杆高BC为____ m（结果保留根号）．
——The little girl often has nothing for breakfast, ________she?——_______. Because she often gets up late and is afraid of being late for school.
地壳中含量最多的元素是（ ）
