题干

室温时,向一密闭容器中充入2mol SO2和2mol O2,在一定条件下发生反应:2SO2+O2⇌2SO3,该反应达到最大限度时,下列说法正确的是(   )

A:正反应的速率为零

B:SO2完全转化为SO3

C:SO3的物质的量浓度不再变化

D:SO2、O2和SO3的物质的量浓度相等

上一题 下一题 0.0难度 选择题 更新时间:2018-06-22 10:17:32

答案(点此获取答案解析)

C

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阅读理解

    People always think men are more skilled than women in driving. Nowadays women appear to have a positive image of themselves as safer drivers than men.

    In a survey done for insurer MetLife, 51% of women said they drive more safely. The evidence is on their side: Men are 3.4 times more likely than women to get a ticket for careless driving and 3.1 times as likely to be punished for drunk driving. “Women are on average less aggressive and more law abiding (守法的) drivers, which leads to fewer accidents.” the report says. However, not all male drivers share the same opinion. Of the men surveyed by MetLife, 39% claimed male drivers were safer. The findings did back them up on one point: automotive knowledge. The report showed that more men are familiar with current safety equipment such as electronic stability control, which helps prevent rollover accidents.

    Auto safety unavoidably matters to money. Insurance companies focus on what classes of drivers have the lowest dollar amounts of claims, and for now, that mainly includes women. In general, women pay about 9% less for auto insurance than men. A study by the website Insweb also showed that auto insurance rates are lower for women in most states. Among individual states, women get the greatest advantage in Wyoming (where they pay 20% less), South Dakota and Washington, D. C., where their insurance costs are 16% lower.

    “More than 11,900 male drivers died in U.S. traffic accidents in 2009, compared with just under 4,900 women drivers,” according to the study. “Based on miles traveled, men died at a rate of 2.5 deaths per 100 million miles traveled, v.s. 1.7 deaths for women.”