正确答案: D

元素W和M的某些单质可作为水处理中的消毒剂

题目：有X、Y、Z、W、M五种短周期元素，其中X、Y、Z、W同周期， Z、M同主族； X+与M2－具有相同的电子层结构；离子半径：Z2－＞W－；Y的单质晶体熔点高、硬度大，是一种重要的半导体材料。下列说法中，正确的是

解析：D

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举一反三的答案和解析：

[单选题]与广东某特大城市相比，北京城市公路立交桥的设计坡度较小，主要考虑的自然因素是

气候条件

[单选题]根据下面内容，回答 60 ~63 题： BComputer programmer David Jones earns￡35,000 a year designing new computer games， yet he cannot find a bank ready to let him have a credit card(信用卡)．Instead，he has been told to wait another two years，until he is 18．The 16-year-old works for a small firm in Liverpool， where the problem of most young people of his age is finding a job.David’s firm releases(推出) two new games for the fast growing computer market each month.But David’s biggest headache is what to do with his money．Even though he earns a lot, he cannot drive a car, take out a mortgage(抵押贷款)，or get credit cards．David got his job with the Liverpool-based company four months ago，a year after leaving school with six O-levels and working for a time in a computer shop．“I got the job because the people who run the firm knew

He has a handsome income.