在底面半径为6的圆柱内，有两个半径也为6的球面，两球的球心距为13，若作一个平面与两个球都相切，且与圆柱面相交成一椭圆，则椭圆的长轴长为____。

    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).

修改病句

香山的秋天是令人向往的地方。