另一化学研究性学习小组在实验室条件下用以硫酸铜溶液为电解液，用电解的方法实现了粗铜的提纯，并对阳极泥和电解液中金属进行回收和含量测定．已知粗铜中含有少量的锌、铁、银、金等金属和少量矿物杂质（与酸不反应）．

右图给我们的启示是    （　　）         

在桃花的结构中，受精后能发育为果皮和种皮的分别是（    ）

阅读短文，选择正确答案。
    We are students of Yuying Primary School(小学). In our school, there are many teachers and students. There are twenty­six girls and twenty­four boys in our class. Our classroom is big. There are six windows and two doors. The walls(墙) are white. There are two pictures on the wall. A big blackboard is in the front of the classroom. Our desks and chairs are new. Our classroom is very nice. I like it very much.

这是____