下列图形中，能折成正方体的是（  ）

针对农村普遍存在的一些养猪和养鸡农户造成的空气和饮用水污染现象，某村民就农村养殖问题向当地政府写了一封《谁来保护我们的生存环境》的信。当地政府十分重视并依据本地实际采取相应措施。村民给当地政府写信是（    ）

①通过社情民意制度行使监督权

②通过基层民主制度参与民主管理

③通过信访制度积极行使监督权

④公民有序参与社会治理的体现

阅读理解
    American country music is also known as(被称为)country Western music．It has a very long history．It comes from the folk songs of immigrants(移民)from Britain．
    Country music uses simple music and words to express everyday feelings such as loneliness，love，and sadness．That is to say，country music describes life．It talks about friends and enemies，trucks and roads，farms and crops．People in many parts of the world like country music，because everyone can understand what the music is about．
    Country Western music became popular first among cowboys(牛仔)in the American West courttryside．Cowboys had to take care of cows day and night．When they were alone with the cows，they often sang beautiful and peaceful songs to calm the animals and to overcome their own fear．They were not well—educated and so they sang about their daily life in very simpie words．They played guitars，violins，and other instruments．  In the south of America，many people added instruments from their homes，like bottles and spoons．  When cowboys visited their friends and families on holidays like Thanksgiving，they usually sang and played country Western music．
    In recent years，many musicians have made country Western music a little different from the one in the past．These changes make the songs sound even better．Today singers such as Garth Brooks， Reba McEntire，Emmylou Harris，Lyle Lovett，Eddie Rabbitt，LeAnn Rimes，Randy Travis，and a group called Alabama are singing and playing in different styles．They have brought country Western music more and more fans from all over the world．

关于人口迁移“推力”和“拉力”的叙述，正确的是（   ）

下列化学反应吸收热量的是（   ）