2015年11月,珠海市政府向社会各界广泛征集对2016年十件民生实事的建议,一改此前由政府“供菜”的方式,变为由市民“点菜”,得到市民的热烈响应。市民积极参与民主决策（  ）

①有利于政府决策充分反映民意 ②能够避免政府决策出现失误

③有利于促进市民对决策的理解 ④有利于决策满足所有市民利益

 某研究学习小组欲测定石灰石中碳酸钙的质量分数，采用的方法如下：取该石灰石样品20g，把80g稀盐酸分四次加入，实验过程所得数据如表格（已知石灰石样品中含有的二氧化硅等杂质不溶于水，不与稀盐酸反应）．根据实验数据计算：

Mr. Wang is a teacher. He ______ in this school for 20 years.

    Today is Sunday. It's a sunny day. I'm in the park with my best friends Mary and Carol. There are many people in the park. They're doing different kinds of things. Some are walking by the lake. Some are talking under a big tree. Some are singing. Some are dancing on the playground. There are some kids playing tennis. Mary, Carol and I are sitting by the pool. It's really a fun day. The people here are all very happy. They're having a good time.

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