夏天，实验员在实验室里配制了一瓶饱和的硝酸钾溶液并密封放置，到了冬天发现瓶底有大量的晶体析出。这是因为（  ）

在两块相同的玻璃片上，小明同学分别滴一滴质量相同的水，如图所示．观察图中情景可知，他主要研究蒸发快慢是否与（  ）

在社会诚信体系建设实践中，扬州市在诚信政府建设、信用法规建设、信用信息平台建设、市场化运作机制建设、消费者放心城市建设等方面取得了较好成绩。建立诚信社会的基础是（     ）

阅读下面短文，掌握大意，然后从A、B、C、D四个选项中选出最佳选项。    I was feeling a little blue because my mother had lost her job.
    One day, while I was 1 on the street, I heard piano music and singing rising above the noise of the people. I walked more slowly to 2 where it was coming from. Then I saw a young lady sitting at a piano.
    She was singing songs about love, 3 yourself and keeping on trying. The way she was singing made me a little comfortable. I stood there 4, watching her playing on such a crowded New York square. I thought that she must be 5 enough to perform(表演) in front of so many people.
    She noticed me. I walked over and told her how good her 6sounded. "Thank you." she said.
    "I am going through a hard time, 7 you made me hopeful again." I said to her.
    "I'm glad that I could help," she answered. "Why are you so 8?"
    "Well, my mum lost her job, and I'm not so sure what to do……"
    "Did you notice the 9 you were walking? Your head was down." she said. "Don't be worry, because10comes in different ways and if your head is down, you might not see it. You should11 more …… lift(抬) your head up. "
    I looked 12 her, surprised at how she was encouraging(鼓励) me. "13 are you playing the piano here?" I asked her with a smile.
    She 14 that she saw a lot of unhappy people in the world and she tried to make 15 happy by playing music.
    I smiled a little wider, realizing that no difficulties could stop me from going on.

按下面的要求设计一个徽标。

①给徽标起一个名字。

②体现一个主题。

③可以全部或部分是轴对称图形。