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如图所示,人眼隔着偏振片B、A去看一只电灯泡S,一束透射光都看不到,那么,以下说法中哪些是正确的(    )                                                                                                                           

                                                                                

    A.  使A和B同时转过90°,能够看到透射光

    B.  单使B转过90°过程中,看到光先变亮再变暗

    C.  单使B转过90°过程中,看到光逐渐变亮

    D.  单使A转动时,始终看不到透射光

                                                                                                                                  

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