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).

汉语的虚词主要有____、____、____、____和____五类。虚词虽然没有实在的词汇意义，但有重要的____。

已知数轴上三点A，O，B表示的数分别为﹣3，0，1，点P为数轴上任意一点，其表示的数为x．

（1）如果点P到点A，点B的距离相等，那么x=____ ；

（2）当x=____ 时，点P到点A，点B的距离之和是6；

（3）若点P到点A，点B的距离之和最小，则x的取值范围是____ ；

（4）在数轴上，点M，N表示的数分别为x₁，x₂，我们把x₁，x₂之差的绝对值叫做点M，N之间的距离，即MN=|x₁﹣x₂|．若点P以每秒3个单位长度的速度从点O沿着数轴的负方向运动时，点E以每秒1个单位长度的速度从点A沿着数轴的负方向运动、点F以每秒4个单位长度的速度从点B沿着数轴的负方向运动，且三个点同时出发，那么运动____ 秒时，点P到点E，点F的距离相等．

党的十八届三中、五中全会进一步要求以周边为基础加快实施自由贸易区战略，形成面向全球的高标准自由贸易区网络。截至2015年，我国已签署并实施14个自贸协定，涉及22个国家和地区，遍布欧洲、亚洲、非洲、和大洋洲。加快实施自由贸易区战略的意义主要在于(     )

①改变我国对外交往方式，解决南北发展不平衡问题

②统筹国内国际两种资源，开创高水平对外开放新局面

③引领经济全球化发展方向，提高肩负国际责任的能力

④推动我国与相关国家和地区互利共赢、共同发展

由直线$x=0$，$x=\frac{2\pi }{3}$，$y=0$与曲线$y=2\sin x$所围成的图形的面积等于(  )