There's no place in the world like Venice, Italy. Situated in the Adratic Sea ,the city of Water is made up of 118 tiny islands. However, it____ (be) in danger of sinking now. Because____city was built on soft soil, it has been sinking under the pressure of its own weight. Scientists say that Venice sinks____ a rate of nearly two inches every 100 years. Mean while, rising sea levels could make Venice go under even faster. Earth's temperature is slowly increasing,____ is causing sea ice to melt and makes the world's waters rise.

    Experts____(rush) to save Venice now because of its rich culture. ¨Many famous artists and opera singers have come from Venice. Some of the world's greatest____(paint) can be found on the city's museum walls," explains Melissa Conn.

    ____(keep) the city afloat, experts want to pump about 40 billion gallons of sea water beneath Venice. While scientists work to get their plan  ____(approve), people in Venice live their normal life. When the tide rolls in the locals have ways of keeping everyone dry. Café owners move tables to____(high) ground, and hotels pass out high boots to guests.____ ( fortune) ,dealing with the rising water does not make the natives discouraged.

已知两圆相外切，连心线长度是10厘米，其中一圆的半径为6厘米，则另一圆的半径是 （   ）

如图，小明在一块平地上测山高，先在B处测得山顶A的仰角为30°，然后向山脚直行100米到达C处，再测得山顶A的仰角为45°，那么山高AD为____ 米（结果保留整数，测角仪忽略不计，$\sqrt{2}$≈1.414，$\sqrt{3}$，1.732）