Na₂SO₄是制造纸张、药品、染料稀释剂等的重要原料．某Na₂SO₄样品中含有少量CaCl₂和MgCl₂，实验室提纯Na₂SO₄的流程如图1所示

（1）加入Na₂CO₃溶液可除去的阳离子是____ （填离子符号），其反应的化学方程式为：____ ．若添加的NaOH溶液和Na₂CO₃溶液过量，可加入适量____ （填名称）除去．

（2）操作a的名称是____ ，该操作中需要用到的玻璃仪器有烧杯、玻璃棒、____ ．

（3）溶液M中的溶质是Na₂SO₄和杂质NaCl，观察图2中溶解度曲线，则操作b是：先将溶液M蒸发浓缩，再降温结晶、过滤．降温结晶的最佳温度范围是____ ℃以下，因为Na₂SO₄溶解度____ ．

It's reported that the passenger ship "Eastern Star" capsized and sank（翻沉) in the Yangtze River _____ June 1st, 2015.

下列实验现象中，描述正确的是（）

    I am an apple. I'm a kind of sweet1You can find me grow in many places of the world, but I can't grow well in very hot places2 very cold places.

    I am not like my cousins 3and bananas. I am rounder than a pear and bananas are4than me. I am delicious,5people all over the world like to eat me. They can usually eat me6washing me. They can also cook me to 7all kinds of food, sometimes they put me in cans（罐头）to send me to other places of the world. Almost everyone can have 8 to buy me because I'm so cheap.

    I can also help people get9 There is a saying10English: An apple a day keeps the doctor away. Don't you think that I'm very great? I have many vitamins（维生素）inside, they are 11for you. I really wish to make you happy and healthy. so don't forget to 12me as often as possible（尽可能经常地）.

    But I also need your13, if you want to make me taste better, you must14 me well. Thank you for your love. I'll try to grow well and15sweeter. Then you will like to eat me a lot more.