Yesterday，Amy and Mary went to the zoo by bike. They saw pandas, lions, monkeys and elephants. They were very happy. They were thirsty, so they bought a watermelon. Amy carried the watermelon on her bike. But it fell off her bike and bumped her foot(脚).

随着人口的快速增长，人类对环境的影响越来越大，带来许多环境问题．

我们经常做广播体操来锻炼身体。一些体操是模仿动物而创造的。下图是一套医疗保健体操，你知道它的发明者是谁吗？（    ）

某公园将一长方形草地改造，长增加20%，宽减少20%，则这块长方形草地的面积（    ）