The US is the fourth largest country in the world. It's smaller than Russia and China. Washington DC is its capital. But it is a quiet city.New York is the biggest city in America and it's one of the biggest cities in the world. It is the east of the US and at the south of the Hudson River(哈德逊河).A large part of the city is on Manhattan Island(曼哈顿岛), a big island in the river. New York has a larger population(人口) than Washington DC. In New York, we can see a famous statue, the Statue of Liberty(自由女神像)

⑴⑵⑶根据短文内容，选择正确的单词或短语把句子补充完整；⑷⑸根据短文内容，选择正确答案。

（Ⅰ）记线段BC的中点为K，在平面ABCD内过点K作一条直线与平面ECF平行，要求保留作图痕迹，但不要求证明．

（Ⅱ）求直线EB与平面ECF所成角的正弦值．

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