如图，两个全等的△ABC和△DEF重叠在一起，固定△ABC，将△DEF进行如下变换：

（1）如图1，△DEF沿直线CB向右平移（即点F在线段CB上移动），连接AF、AD、BD，请直接写出S_△ABC与S_{四边形AFBD}的关系

（2）如图2，当点F平移到线段BC的中点时，若四边形AFBD为正方形，那么△ABC应满足什么条件：请给出证明；

（3）在（2）的条件下，将△DEF沿DF折叠，点E落在FA的延长线上的点G处，连接CG，请你画出图形，此时CG与CF有何数量关系．

Please ____(享用)your dinner.

C

    When we say a person blows his own trumpet(喇叭)，we mean he tells other people how good and successful he is．That is usually an act of arrogance(自大)．But teachers at Wimbledon High School once asked their students to blow their own trumpet．

    “Some students are under too much pressure and they find it difficult to accept that they have been successful．”said Ms. Hanbury, head of this famous all -girls school in London．“They push themselves hard and might never be happy．”That's why the “Blow Your Own Trumpet Week” was held in the school．

    In the“Blow Your Own Trumpet Week”,the teachers asked their students to share their stories of success and failure(失败)．They also asked them to tell how well they did in each subject．In this way, the school wanted to help students to know they were all good at something and that they didn't have to be good at everything．

    Before that, the school ran a“Failure Week”to help students deal with setbacks(应对挫折)．The students learned how to get better from setbacks quickly, so they wouldn't think it was the end of the world if they didn't do well in an exam．

根据材料内容完成下列任务。

 ($\sqrt{2}$+$\sqrt{3}$-$\sqrt{6}$)($\sqrt{2}$-$\sqrt{3}$+$\sqrt{6}$)．