礼仪是交往的产物，语法是说话的产物，逻辑是思考的产物。人们长期形成的做事情的方式和规范，无非是人类知识和经验的总结。这表明(　　)

①文化实质上是一种精神力量

②文化是人们社会实践的产物

③文化素养是逐步培养出来的

④文化现象无时不在、无处不有

两个相同的电阻，分别通以如图所示的正弦交流电和方波形交变电流，两种交变电流的最大值相等，周期相等。则在一个周期内，正弦式交流在电阻上产生的焦耳热Q1与
方波式交流在电阻上产生的焦耳热Q2之比等于

计算．

    Mr. Brown is a teacher. He is from New York, America. He would like（想）to work in China because he likes our country. He thinks Chinese people are very friendly and he likes to live in China. He is happy to work in our school. He likes the school life here. He teaches English. There are 50 students in his class. Mr. Brown is kind. He and his students are good friends, too.
    Now some of Mr. Brown's students play sports on the playground（操场）. Bill and Mike play tennis. Tom and John play ping-pong. The other students play basketball. Mr. Brown is happy to play basketball with them. They have a good time.
阅读上面的短文，根据短文内容，选择最佳选项。   

昼出耕田夜绩麻，村庄儿女各当家；童孙未解供耕织，也傍桑荫学种瓜。这首诗蕴涵的哲理是（  ）