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U、V、W、X、Y、Z是六种常见的短周期主族元素,其中W、X、Y、Z原子半径随原子序数的变化如图所示:

已知Y的最高价氧化物对应的水化物可与其简单氢化物反应可生成离子型晶体的一种盐;Z是地壳中含量最多的元素;W原子的最外层电子数与Ne原子的最外层电子数相差1;U原子最外层电子数是次外层电子数的两倍;V为原子核内有12个中子的二价金属,当2.4克V与足量热水反应时,在标准状况下放出气体2.24L;请回答下列问题:

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    The kids in a village in Ethiopia wear dirty, ragged clothes. They sleep beside cows and sheep in huts made of sticks and mud. They have no school. Yet they all can chant the English alphabet, and some can make words.

    The key to their success: 20 tablet computers(平板电脑) dropped off in their Ethiopian village in February by a U.S. group called One Laptop Per Child.

The goal is to find out whether kids using today's new technology can teach themselves to read in places where there are no schools or teachers. The Massachusetts Institute of Technology researchers analyzing the project data say they're already amazed. “What I think has already happened is that the kids have already learned more than they would have in one year of kindergarten,” said Matt Keller, who runs the Ethiopia program.

    The fastest learner—and the first to turn on one of the tablets—is 8-year-old Kelbesa Negusse. The device's camera was disabled to save memory, yet within weeks Kelbesa had figured out its workings and made the camera work. He called himself a lion, a marker of accomplishment in Ethiopia.

With his tablet, Kelbasa rearranged the letters HSROE into one of the many English animal names he knows. Then he spelled words on his own. “Seven months ago he didn't know any English. That's unbelievable,” said Keller.

    The project aims to get kids to a stage called “deep reading,” where they can read to learn. It won't be in Amharic, Ethiopia's first language, but in English, which is widely seen as the ticket to higher paying jobs.