①图形的形状；②图形的位置；③线段的长度；④角的大小；⑤垂直关系；⑥平行关系．

不发生改变的有____（把你认为正确的序号都填上）．

    There will be many changes in our life in the future. We will____ flying cars to work. We will travel to ____ . Maybe we will ____ live in space. Students won't ____  schoolbags to go to school any more. They will learn on ____ at home. And there will be robots in our home. The robots will help us do all the housework. Life will be great at that time.

已知A、B、C、D四种短周期元素的核电荷数依次增大．A原子s轨道电子数是p轨道电子数的两倍，C原子的L能层中有两对成对电子，C、D同主族． E、F是第四周期元素，且E位于周期表中ds区，F原子核外有33种不同运动状态的电子．根据以上信息用相应的元素符号填空：

下列各元素中，化合价的最高正价数最大的是（　　）