题目

甲、乙两个小组各10名学生的英语口语测试成绩如下：(单位：分)甲组：76,90,84,86,81,87,86,82,85,83;乙组：82,84,85,89,79,80,91,89,79,74试分析哪个小组学生的成绩比较整齐？ 答案：解析：由于数据较大,确定替换xi′=xi-a,其中a=80(因两组数据都在80左右波动).列表：甲组：xi76908486818786828583合计xi′-4104617625340xi′2161001636149364259292乙组xi82848589798091897974合计xi′2459-10119-1-632xi′241625811012181136366则=［292-10()2］=13.2,=［366-10(()2］=26.36.由＜表明：甲组学生的成绩比乙组学生的成绩整齐.①Researches show what we already suspected: Three out of four babies who died of SIDS(婴儿猝死) involved co-sleeping. We’ll say it again. The safest course is not to sleep with babies. ②We know the argument: Bad parenting, not co-sleeping, is to blame for the dozens of babies’ deaths. Some parents stick to co-sleeping because it helps them bond with their newborns. They say those who give co-sleeping a bad name either had been drinking, used drugs or were too tired to notice that they rolled over on their children. ③But, most of the cases did not involve drugs or alcohol. There’s a “but” here, however. Submitting to a test for drugs or alcohol in these cases is voluntary, so it’s difficult to know with certainty. ④Organizations like the Black Health Coalition and others have explained the safe way to co-sleep. While we understand those arguments, we also know that mistakes can happen and that it only takes one time for something to go terribly wrong. The risk outweighs the benefit. ⑤In all likelihood, parents will continue to co-sleep, and some will do so without ever having an incident, but babies are too vulnerable(易受伤的) for parents to take such chances. Therefore, the best place for babies to sleep is in their own beds, on their backs, with no pillows, blankets or toys. No parent wants a tragedy to occur. The best way to make sure the tragedy doesn’t happen is to allow babies to sleep alone in their own cribs.                                          1.According to the author, most of the SIDS cases happened because of ________. A. drugs    B. co-sleeping    C. drinking     D. bad parenting 2. Some parents think sleeping with their babies can ________. A. keep the babies healthy B. give co-sleeping a good name C. prevent themselves from drinking D. develop a good relation with their babies 3. The author holds the opinion that ________. A. parents can sleep with babies, but cautiously B. co-sleep helps to bring babies closer to parents C. parents can’t take chances to sleep with their babies D. accidents only happen to those careless parents 4. Which of the following best describes the structure of the text? A.  ①         B.  ①②      C.  ①         D.  ① ↙↘              ↓         ↙↓↘        ↙↓↓↘ ②③  ④        ③④    ②③④       ②③④⑤ ↘ ↙         ↓        ↘↓↙ ⑤               ⑤          ⑤