在重庆有堪称“世界第一水文站”的是______。
参考答案：涪陵白鹤梁
正方形厚纸ABCD的边BC上有一点P，折纸使点A重合与P，若AB=24cm，BP=7cm，则折痕EF的长为______cm．
Rio De Janeiro, ___________the right to host the 2016 Olympic Games, will be occupied in building stadiums.
A．winning
B．won
C．having won
D．to win
