（1）铝是地壳中含量最多的金属元素，在元素周期表中铝元素的信息如图所示：

①铝的原子结构示意图为____ ；

②铝离子的核外电子数为____ ；

③工业上用电解熔融的方法冶炼铝，化学方程式为：2Al₂O₃4Al+3O₂↑ ，该反应属于基本反应类型中的____ ．

（2）要除去下列混合物中的杂质（括号内为杂质），写出除去杂质的化学方程式：

①Ag（Cu）____ ；②CO₂（CO）____ ．

    Almost every Chinese person can recite(背诵) the two lines of the famous poem, "Every grain on the plate comes from hard work". But sadly, many of us don't actually get the real meaning of these lines: Don't waste food.

    A CCTV program reported that the food Chinese people throw away every year is enough to feed 200 million people for a year. Do we have too much food? Absolutely not. According to the UN World Food Program, there were 925 million hungry people around the world in 2011, especially in developing countries. Six million children die of hunger every year.

    Chinese people are well-known for being friendly and generous. Many even feel that they lose face if their guests have eaten all the food on the table. Luckily, a number of people have realized the importance of saving food. What should we do in our daily lives to waste less food?

    1 Don't order too much in a restaurant. Only order as much as you want to eat. If you cannot eat all the food you ordered, take the rest of it home.

    2 Don't leave any food in your bowls, while having meals.

    3 Keep an eye on what food you have at home. Don't buy too much, especially for vegetables and fruit.

有性生殖生物的后代性状差异，主要来自于基因重组，下列过程中哪些可以发生基因重组（　　）