如图，矩形ABCD的边AB=1，BE平分∠ABC，交AD于点E，若点E是AD的中点，以点B为圆心，BE长为半径画弧，交BC于点F，则图中阴影部分的面积是（   ）

如图所示，质量为m的物体从半径为R的半球形碗边向碗底滑动，滑到最低点时的速度为v，若物体与碗的动摩擦因数为μ，则物体滑到最低点时受到的摩擦力的大小是
 

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     Comedy King Stephen Chow's upcoming film 'The Mermaid' has released its first trailer（预告片）.
     Actor Deng Chao, who plays the leading role in this film, appeared in the trailer by reporting his findings of a mermaid to the police.
    A series of hand-painted posters by the director come out along with the trailer.
    Set plot（情节） in the modern world, the film describes the story of a biological professor, who was saved by a mermaid, and then falls in love with the mermaid.
    So far, the film has unveiled（公开） its first official poster, with a photo of crashing waves, the title, and the director's name.
    The film also stars Kris Wu, Show Luo, and the new-face actress Lin Yun as the titular character.
    'The Mermaid' is scheduled to be released during China's Lunar New Year, on February 8th.

要把制成的洋葱表皮细胞临时装片进行染色，最准确的方法是（    ）

在方程 $\frac{1}{x+1}=\frac{1}{y-1}$ ， $\frac{1}{x}+1=\frac{1}{x-2}$ ， $\frac{x}{b}+\frac{y}{a}=1$ ， $\frac{ax-by}{a^2+b^2}=\frac{bx+ay}{a^2-b^2}$ （a，b为已知数）中，分式方程有（   ）