根据短文理解，从A、B、C、D四个选项中选择最佳填空。

    Hello. I'm Tom. I'm a middle school student. It's nice to meet you here. First, let me tell you 1 my family. Five people are in my 2, my mother, my father, my two sisters and I. But I have 3 brother.

    My father is a worker. My mother is 4 English teacher. My sisters are sixteen. I'm fourteen. We go to the same school. We all like 5 football games. We think they're interesting. I also have a cat. 6 name is Mimi.

    There is a big tree and some small trees  (树) around my house. The big one is a pear tree and the small ones are apple 7.  8 a photo of my room. Please have a look. When  当) you 9 my room, you can see three English dictionaries on my desk. I like 10 very much.

一些自然灾害的发生过程中常常诱发一系列的次生灾害，表现为自然灾害发生的（   ）

确定的事件有____；随机事件有____，在随机事件中，你认为发生的可能性最小的是____，发生的可能性最大的是____．(只填序号)

如图甲所示，电源电压U=6V，S为单刀双掷开关，小灯泡L的电阻R_L=10Ω，R为某种压敏电阻，其阻值R与压力F成反比关系，（如图乙所示），R的正上方装有一电磁铁P，其线圈电阻不计

如图（1），在△ABC中，∠ACB=90°，AC=BC=$\sqrt{2}$，点D在AC上，点E在BC上，且CD=CE，连接DE．

（1）线段BE与AD的数量关系是，位置关系是．

（2）如图（2），当△CDE绕点C顺时针旋转一定角度α后，（1）中的结论是否仍然成立？如果成立，请给予证明；如果不成立，请说明理由．

（3）绕点C继续顺时针旋转△CDE，当90°＜α＜180°时，延长DC交AB于点F，请在图（3）中补全图形，并求出当AF=1+$\frac{\sqrt{3}}{3}$时，旋转角α的度数．