Are you facing a situation that looks impossible to fix (修理)？

    In 1969, the pollution was terrible along the Cuyahoga River near Cleveland, Ohio. It ____(be) unimaginable that it could ever be cleaned up. The river was so polluted that it____(actual) caught fire and burned. Now, years later, this river is one of____most outstanding examples of environmental cleanup.

    ____the river wasn't changed in a few days or even a few months. It took years of work____(reduce) the industrial pollution and clean the water. Finally, that hard work paid off and now the water in the river is____(clean) than ever.

    Maybe you are facing an impossible situation. Maybe you have a habit ____is driving your family crazy. Possibly you drink too much or don't know how to control your credit card use. When you face such an impossible situation, don't you want a quick fix and something to change immediately?

    While there are____(amazed) stories of instant transformation, for most of us the____(change) are gradual and require a lot of effort and work, like cleaning up a polluted river. Just be____(patience).

如图所示为一水平直路面，AB的长度为x₁=25m，BC的长度为x₂=97m，一辆汽车（视为质点）从A点由静止启动，开始做加速度大小为a₁=2m/s²的匀加速直线运动，进入BC段时先做加速度大小为a₂=1m/s²的加速运动，运动到离C点适当距离处开始以大小为a₃=2m/s²的加速度减速运动，汽车恰好能停在C点，求：

如图，CD平分∠ACB，DE∥BC，∠AED=80°，求∠EDC的度数．