不等式组$\left\{\begin{array}{c}{x}^2-1<0\\ x^2-3x\ge 0\end{array}\right.$的解集是（ ）

2007年11月16日，孟加拉国发生强热带风暴，造成巨大的财产损失和人员伤亡。据此回答题。
强热带风暴可能造成的灾害有（  ）
①大风  ②寒潮  ③洪涝  ④干旱⑤风暴潮  ⑥暴雪

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    John had a busy weekend. On Saturday morning, he went to the library and studied math. On Saturday afternoon, he went to the park. He played tennis with his friend. Lisa was busy on Saturday, too. She cleaned her room in the morning. In the afternoon, she wrote a letter to her cousin(表妹).

    On Sunday morning, John and Lisa read books at home. On Sunday afternoon, they practiced English. In the evening, they saw an interesting talk show with their parents. They had great fun.

海洋中蕴含丰富的资源．

（1）海水淡化是解决淡水资源不足的重要方法．下列方法中，可以使海水变为淡水的是____ （填字母序号）．

A．滤纸过滤      B．吸附      C．沉降     D．蒸馏

（2）从海水中提炼出来的重水（D₂O）可作原子能反应堆的中子减速剂和热传热介质．重水中重氢原子（D）的相对原子质量是2，则重水中氢元素的质量分数为____ ．

（3）从海水中制备纯碱和金属镁的流程如图所示：

回答下列问题：

①步骤Ⅴ中所加试剂是____ ．

②粗盐水中主要含有CaCl₂、MgSO₄等可溶性杂质，可加入下了物质，利用过滤等操作进行除杂，则加入下列三种物质的先后顺序为____ （填字序号）．

a．适量的盐酸       b．稍过量的Na₂CO₃溶液     c．稍过量的Ba（OH）₂溶液

③第Ⅲ歩反应的化学方程式是____ ．

④在海边用贝壳作原料制生石灰，比用石灰石作原料的优点是____（写一条）．