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问题 选择题

某航空公司开通了加拿大多伦多(43°N、80°W)——泰国曼谷(13°N、100°E)的直达国际航班。据此回答：  

该航班飞机选择的是最短航线，若飞机时速为800Km小时，则飞行时间约为

A．17小时

B．32小时

C．14小时

D．22小时

答案

答案：A

本题考查大圆航线。根据两点之间的经纬度判断两点位于同一经线圈上，则大圆航向为经线圈。两者之间纬度数间隔为47°+77°=124°，之间的距离为124×111km，飞机时速为800Km小时，所以需要飞行约17小时。所以本题选择A选项。

选择题

根据下面三个化学方程式判断有关物质的性质比较正确的是

   [ ]

①I2+SO2+2H2O=H2SO4+2HI

②2FeCl2+Cl2 = 2FeCl3

③2FeCl3+2HI= 2FeCl2+2HCl+I2

A．氧化性：I2> H2SO4>Cl2> Fe3+

B．还原性：Cl->Fe2+>SO2>I-

C．氧化性：Cl2> Fe3+ >I2> H2SO4

D．还原性：SO2> Fe2+ > I- >Cl-

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单项选择题

Drug use is rising dramatically among the nation’ s youth after a decade of decline. From 1993 to 1994, marijuana use among young people (1) from 12 to 17 jumped 50 percent. One in five high school seniors (2) marijuana daily. Monitoring the Future, which (3) student drug use annually, reports that negative attitudes about drugs have declined for the fourth year in a row. (4) young people see great risk in using drugs. Mood-altering pharmaceutical drugs are (5) new popularity among young people. Ritalin, (6) as a diet pill in the 1970s and now used to (7) hyperactive children, has become a (8) drug on college campuses. A central nervous system (9) , Ritalin can cause strokes, hypertension, and seizures. Rohypnol, produced in Europe as a (10) tranquilizer, lowers inhibitions and suppresses short-term memory, which has led to some women being raped by men they are going out with. (11) taken with alcohol, its effects are greatly (12) . Rock singer Kurt Cobain collapsed from an (13) of Rohypnol and champagne a month before he committed (14) in 1994. In Florida and Texas, Rohypnol has become widely abused among teens, who see the drug as a less expensive (15) for marijuana and LSD. Alcohol and tobacco use is increasing among teenagers, (16) younger adolescents. Each year, more than one million teens become regular smokers, (17) they cannot legally purchase tobacco. By 12th grade, one in three students smokes. In 1995, one in five 14-year-olds reported smoking regularly, a 33 percent jump (18) 1991. Drinking among 14-year-olds climbed 50 percent from 1992 to 1994,and all teens reported substantial increases in (19) drinking. In 1995, one in five 10th graders reported having been drunk in the past 30 days. Two-thirds of high school seniors say they know a (20) with a drinking problem.

2（）

A.tastes

B.smokes

C.injects

D.takes
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