若带正电荷的小球只受到电场力的作用，则它在任意一段时间内（   ）

根据短文理解，选择正确答案。

    Five years ago, David Smith wore an expensive suit to work every day. “I was a clothes addict(有瘾的人),” he jokes. “I used to carry a fresh suit to work with me, so I could change if my clothes got wrinkled(有褶皱的).” Today David wears casual clothes (便装) to the office. He hardly ever wears a necktie. “I am working harder than ever.” David says, “and I need to feel comfortable.”

    More and more companies are allowing their office workers to wear casual clothes to work. In the United States, the change from formal to casual office wear has been gradual. In the early 1990s, many companies allowed their employees to wear casual clothes on Friday. This became known as “casual Friday”. “What started out as an extra one-day-a-week benefit for employees has really become an everyday thing.” said business consultant Maisly Jones.

    Why have so many companies started allowing their employees to wear casual clothes? “One reason is that it's easier for a company to attract new employees if it has a casual dress code.” “A lot of young people don't want to dress up for work,” says Owen Black, the owner of a software company, “so it's hard to hire people if you have a conservative (保守的) dress code.” Another reason is that people seem happier and more productive when they are wearing comfortable clothes. In a study conducted by Levi Company, 85 percent of employers said that they believe that casual dress improves employee morale (心境, 士气). Only 4 percent of employers said that casual dress has a negative influence on productivity. Supporters of casual office wear also argue that a casual dress code helps them save money. “Suits are expensive, if you have to wear one every day,” one person said. “For the same amount of money, you can buy a lot more casual clothes.”

爱国主义是民族精神核心，下列能体现这一核心的说法有（　　）

    Residents in the poorest counties in the U.S. face a life expectancy up to decade shorter than their counterparts in the wealthiest areas, according to a study published in the American Journal of Public Health.

    Researchers from East Tennessee State University wanted to better understand how socioeconomic status was associated with heath outcomes. To find out they divided the country's 3,141 counties into 50 new 'states' (with 2 percent of the counties in each) based on household income as opposed to geographic proximity (接近).

    The researchers broke down the data by county since they found state-level data may hide some 'impact of socioeconomic differences on both the best-off and worst-off counties.' They then examined health data from the wealthiest and poorest 'states' (top and bottom 2 percent) to see how residents differed on factors like smoking, clinical care and excessive drinking. Researchers found that there was nearly a 10-year gap in the life expectancy of men with an average of 79.3 years in the wealthy counties compared to 69.8 years in the poorest. For women, the difference was slightly less - 83 years in the wealthiest counties and 76 years in the poorest.

    The study authors caution that while they found a connection between socioeconomic status and health outcomes, they did not analyze cause and effect. But they suggest that the data shows how policy makers should not just focus on state-wide initiatives (主动性) but more targeted efforts to help those most at risk. “With limited resources, methods of pinpointing the poorest counties can assist in the allocation of resources and programs to those communities that are in the greatest need,'' the study authors wrote.