题干

下列实验“操作和现象”与“结论”对应关系正确的是(   )

选项

实验操作及现象

实验结论

A

将碘水和四氯化碳的混合溶液置于分液漏斗中并振荡、静置.溶液分层,上层呈紫红色,下层几乎无色.

碘在四氯化碳中的溶解度大于在水中的溶解度

B

将表面滴有几滴水的蔗糖和一定量的浓硫酸混合并搅拌.蔗糖膨胀变黑,产生有刺激性 气味的气体.

浓硫酸具有脱水性和强氧化性

C

在稀硝酸和过量的铜片反应后的溶液中,滴入少量稀硫酸.剩余铜继续溶解,并有气泡产生.

稀硫酸也可将铜氧化

D

用洁净的铂丝蘸取某盐溶液在酒精灯火焰上灼烧.观察到酒精灯火焰呈黄色.

盐溶液中一定含有 Na+,无 K+

A:A 

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2019-04-18 02:44:27

答案(点此获取答案解析)

B

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阅读理解

    The smart phone(智能手机)company Xiaomi Technology was set up in Beijing in 20 1 0.

Now it has become one of leading mobile phone companies in China. Some people skip work and school to wait in line to buy its main product:Mi phones.

    The man behind this craze(狂热)is Lei Jun. The 47-year-old is the co—founder(联合创始人) and CEO of Xiaomi. Lei was born in Xiantao, Hubei, in 1969. At the age of l 8. he entered Wuhan University to study computer science. A book that he read there changed his life. It was Fire n the Valley, which tells the story of the co—founder of Apple, Steve Jobs. Encouraged by the book. the 21—year—old set up a company. But it soon failed because he lacked(缺少)a long—trill plan.

After graduation, Lei joined King soft, a software company. In l 6 years, he became one of the top IT company leaders. But that's not the only thing he wanted. “I had my dream not realized and it was calling for me every night, ”said Lei. At the age of 38, he left Kingsoft and started his own company. This time, he knew what would make a promising new company:following the trends but keeping innovating(创新). He entered the smart phone market.

  Lei is a big fan of the iPhone. But instead of creating a copy of it, he kept thinking about how to make it better.

    At the age of 41, he co—founded Xiaomi. Now,  there are more than l4 million Mi phone users. Lei helped make online shopping popular in China. “People become great because they have dreams, ”said Lei.