题干

开启啤酒瓶盖瞬间伴有“嘭”的一声,瓶口有一股“白烟”,下列说法中正确的(   )

A:瓶的内外温度相等,啤酒内能不变

B:瓶内的气体对外做功,啤酒内能增加

C:瓶口的“白烟”是瓶内二氧化碳液化形成的

D:瓶口的“白烟”是瓶口水蒸气液化形成的

上一题 下一题 0.0难度 选择题 更新时间:2018-12-10 06:31:21

答案(点此获取答案解析)

D

同类题4

“Am I my brother's keeper?" The question comes from the Bible(圣经). In the Bible, Cain kills his brother Abel. When God asks Cain where Abel is, he replies, "I don't know. Am I my brother's keeper?”by which he means, “Am I responsible (有责任心的) for my brother—his safety and health?”The answer, of course, is “Yes, you are.”

   This sense of responsibility for others is basic to all good societies. And also it is basic to what we call “civil(文明的) society”. China is now working on building a civil society and the high schools in Shanghai want students to take part in that through volunteering. They are supposed to do sixty class hours of volunteer work before graduation. This is something new in China, but it is not new in other countries.

In theCanadian province of Ontario, high school students are required to do forty hours of volunteering. In some American states, the volunteering requirement is one hundred hours. These students spend about an hour a week during the school year and summer vacations, helping the poor, the sick and the old. They also teach young children to read and help to clean up the environment. And studies have shown that this volunteering experience influences students a lot after graduation.

   Some of you may be thinking, “Gee, sixty class hours is a lot. How can I find the time?” In fact, if you finish it in three years, you only need to do the work about three class hours a month. And the time is well spent if it helps you realize that “being your brother’s keeper” makes you a better person and makes society a better place for everyone.