阅读下文，回答问题
                                                                                                  On the beach
    It is a fine day. A lot of people go to the beach to enjoy sunshine. Some people are swimming like fishes in the sea. On the beach，some young people are playing volleyball.
    Some of them are lying under the coconut trees. And some old people are chatting with each other. What are the children doing? Look! They are making castles with spade and sand. They are having fun。
⑴⑵⑶⑷⑸根据短文内容，判断正误；⑹根据短文内容填空。

已知i是虚数单位，复数 满足 $\frac{\text{2}+z}{\text{i}-z}$ = $1+2\text{i}$ ，则复数z的共轭复数为（    ）

据权威部门推测，到2018年，中国经济、美国经济对世界经济增长的贡献率将分别达到26．4%、15．7%。这表明（    ）

根据加法算式，写出减法算式．

如图所示，在一熟苹果切片上分别滴上1滴碘水和银氨溶液，颜色变化如图所示，根据这些实验现象的下列推断正确的是