1/2+1/6+1/12+1/20+1/30+1/42( )A．-1/2 B．1/4 发布时间：2017-12-22 04:59 │ 来源：www.tikuol.com 题型：单项选择题 问题： 1/2+1/6+1/12+1/20+1/30+1/42( )A．-1/2B．1/42C．1/7D．6/7
题型：单项选择题 阅读理解。 Do you have to carry a heavy bag to school? Does it make your back (背部) hurt? Well, students at a high school in Kansas (堪萨斯州), America, have a meeting with their city's mayor to complain (抱怨) about their heavy bags. They say their bags are giving them headaches, and making their necks (脖子) andbacks hurt. The mayor says he is very sorry. He says students may do more of their homework on theInternet (国际互联网) to give their backs a rest. 1. A heavy bag may make students . [ ]A. headache B. earache C. toothache D. A, B and C 2. Kansas is in . [ ]A. China B. America C. Australia D. Canada 3. The students talk about their heavy bags to . [ ]A. the mayor B. their parents C. their teachers D. their friends 4. "Mayor" in Chinese means . [ ]A. 校长 B. 队长 C. 市长 D. 省长 5. The mayor says . [ ]A. he has a headacheB. he wants the students to do more homework C. he is sorry D. he has to work hard 查看答案
题型：单项选择题 设来自正态总体X～N（μ，1.52）的样本值：49.7，50.6，51.8，52.4，48.8，51.1，51.2，51.0，51.5。则μ的置信度为0.95的置信区间为（）。A．[49.92，51.88]B．[49.7，51.88]C．[50.6，51.88]D．[49.92，51.1] 查看答案