题干

甲、乙两种物质的相对分子质量分别为M和N.若将甲、乙两种物质的溶液混合,当溶液中甲与乙的质量比为2M:N时,充分反应后溶液的pH=7,则甲和乙应是下列物质中的(  )


A:HCl和KOH

B:Na2CO3和Ba(OH)2

C:HCl和Ca(OH)2  

D:Ca(OH)2和H2SO4

上一题 下一题 0.0难度 选择题 更新时间:2018-03-06 09:06:10

答案(点此获取答案解析)

C

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    Your glasses may someday replace your smartphone, and some New Yorkers are ready for the switch. Some in the city can't wait to try them on and use the maps and GPS that the futuristic eyewear is likely to include.

    “ I'd use it if I were hanging out with friends at 3 a. m. and going to the bar and wanted to see what was open,” said Walter Choo, 40, of Fort Greene.

    The smartphone-like glasses will likely come out this year and cost between $250 and $600, the Times said, possibly including a variation of augmented(增强的) reality, a technology already available on smartphones and tablets (平板电脑) that overlays information onto the screen about one's surroundings. So, for example, if you were walking down a street, indicators would____showing you the nearest coffee shop or directions could be plotted out and come into view right on the sidewalk in front of you.

    "As far as a mainstream consumer product, this just isn't something anybody needs,” said Sam Biddle, who writes for Gizmodo.com.  “ We're accustomed to having one thing in our pocket to do all these things,” he added, “and the average consumer isn't gonna be able to afford another device (装置) that's hundreds and hundreds of dollars.”9to5Google publisher Seth Weintraub, who has been reporting on the smartphone-like glasses since late last year, said he is confident that this type of wearable device will eventually be as common as smartphones.

    “It's just like smartphones 10 years ago,” Weintraub said. “A few people started getting emails on their phones, and people thought that was crazy. Same kind of thing. We see people bending their heads to look at their smartphones, and it's unnatural,” he said. “ There's gonna be improvements to that, and this a step there.”