题目

Global warming is having a great effect on hundreds of species around the world. No one knows   61   (exact) what will happen in the future   62   global warming continues. As the Earth becomes   63   (warm), weather will become more unpredictable. Increased temperatures will cause the polar ice to melt, raising sea level and   64   (result) in more floods. The sea level   65   (rise) six to eight inches in the past 100 years. Hurricanes will be more   66   (power) and animals   67   require colder climates will be forced to move to other areas or will beco如图1，在Rt△ABC中，∠C=90°，BC=3，AC=6，D，E分别是AC，AB上的点，且DE∥BC，DE=2，将△ADE沿DE折起到△A1DE的位置，使A1C⊥CD，如图2。 （1）求证：A1C⊥平面BCDE；（2）若M是A1D的中点，求CM与平面A1BE所成角的大小；（3）线段BC上是否存在点P，使平面A1DP与平面A1BE垂直？说明理由。