①“民之所望，政之所向”，柴米油盐酱醋茶，就业求学购房医疗，这些群众魂牵梦绕的问题，看似“鸡毛蒜皮”的小事，却是关乎民心的大事。

②网络文学南北对话论坛上，作家们围绕“走向新生态：网络文学的深耕与广拓”的主题，畅谈新时代的网络文学如何为文艺繁荣添砖加瓦。

③社会发展的事实表明，越南人民和中国人民的友谊和密切关系是永恒的、牢不可破的，是任何人不能离间和阻挠的。

④日本“神钢事件”反映了当今“日本制造”的商家，为了维持自己的竞争优势，选择孤注一掷地赌押输赢，以次充好来降低成本的现象。

⑤文章称，对美国很多批评者而言，特朗普可谓撕下了美国的面具，露出这个世界大国充满疑虑，肆无忌惮，且自私自利的真面目。

⑥群山逶迤，竹海莽莽，茶树连片，幢幢紅頂白墙的阁楼各分秋色；走进安吉县余村，水渠水塘景观摩肩接踵，让你目不暇接。

    I gain a lot of rewarding experiences from some social activities. Our local Community Youth Club is a very popular organization with young people in my town. I have been a member for four years now and I've taken part in a lot of interesting projects,____include fun activities such as holiday camps and discos. We have organized sports competitions and we have even made a video.

    But it isn't all just enjoyment, we have also started doing social work to help people in our neighborhood. We____(organize) activities for small children during the holidays. We have also formed a special support group to help young people stop____(smoke).

    We are particularly proud of the most recent group we have created. It organizes regular visits____the local old people's home. My class spent an afternoon at a home and everyone found the visit very rewarding. The old people there were____(talk) and they told us their personal stories____(cheer) .

    During our visit, the home was filled with ____(laugh). But we realized that life wasn't always easy .Some of them were in poor health and were very

____ (happy).

    Many young people like me do not live with our grandparents and we have little contact with elderly people. As a result, many young people don't know____

    they are like. After this visit, my friends and I decided that we should do____to help improve the quality of their lives.

①CH₃Cl、②CH₂C1₂、③CHCl₃、④CCl₄．

化学世界千变万化。
请写出下列反应的文字表达式，并在物质下方标出相应的化学式，回答有关问题。
(1)电解水实验：
____，正极和负极产生的气体体积比为____ 。
(2)加热碳酸氢铵：
____，该反应属于____ (填基本反应类型)。
(3)镁带在氧气中燃烧：
____ ，此反应过程中____ (选填“吸收”或“放出”)热量。