1925年12月，苏联提出了“社会主义工业化”方针，斯大林认为，不是发展任何一种工业都是工业化，工业化的中心，工业化的基础，是发展重工业（燃料、金属等等），就是发展生产资料的生产，发展本国的机器制造业。从材料中可以看出这一方针的特点是（    ）

    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).

鸡的只数：____

鸭的只数：____

鹅的只数：____

兔的只数：____

____

∠A=70°，则∠DOE=____°．

已知a+b=2，ab=2，则 $\frac{1}{2}$ a³b+a²b²+ $\frac{1}{2}$ ab³的值为____．