如图,已知四边形ABCD,对角线AC和BD相交于O,下面选项不能得出四边形ABCD是平行四边形的是( )
A:AB∥CD,且AB=CD
B:AB=CD,AD=BC
C:AO=CO,BO=DO
D:AB∥CD,且AD=BC
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正方形ABCD固定,将正方形OEFG绕点O逆时针旋转α角(0°<α<360°)得到正方形OE′F′G′,如图2.
①在旋转过程中,当∠OAG′是直角时,求α的度数;
②若正方形ABCD的边长为1,在旋转过程中,求AF′长的最大值和此时α的度数,直接写出结果不必说明理由.