题干

下列说法正确的是(   )

A:如果物体运动过程中重力做功为﹣1J,则物体的重力势能减少量为1J

B:如果物体从A沿直线运动到B的过程中克服重力做功为1J,则从B沿直线运动到A的过程中克服重力做功仍然为1J

C:物体受拉力作用向上运动,拉力做的功是1J,物体重力势能的增加量可能不是1J

D:如果物体从A沿直线运动到B的过程中克服重力做功为1J,则物理从A沿某曲线运动到B的过程中克服重力做功一定大于1J

上一题 下一题 0.0难度 选择题 更新时间:2015-08-28 03:59:23

答案(点此获取答案解析)

C

同类题3

任务型阅读

    The word “pub” is short for public house. There are around 60,000 pubs in the U.K. One of the oldest pubs, Fighting Cocks in St. Albans, Herts, is located in a building that dates back to the eleventh century.

    ____ People talk, eat, drink, meet their friends and relax there. Pubs often have tow bars, one usually quieter than the other, and many have a garden where people can sit in summer.____

    Groups of friends normally buy “rounds” of drinks.____It is sometimes difficult to get served when pubs are busy: the bar staff will usually try and serve those who have been waiting the longest at the bar first.

    Most pubs offer a complete range of beers, local and imported, with German, Belgian and French beers being in demand.____As a matter of fact, pubs sell soft drinks, too.

    The legal age to purchase alcohol is 18 in the U.K.____But they must be with an adult and the adult orders it.

    It is illegal to sell alcohol to someone who already appears drunk. Fourteen-year-olds may enter a pub unaccompanied by adults if they order a meal. Children may enter a pub with their parents until 9 p.m., which lets families enjoy reasonably priced pub meals together. And it also allows pubs to play their traditional roles as community centers. Customs in British pubs differ from those in American bars. In most pubs in the U.K., you must go to the bar to order drinks and food and pay for your purchases immediately.

A. Most people might think pubs are places where people simply drink alcohol.

B. The person whose turn it is will buy drinks for all the members of the group.

C. People aged 16 and 17, with the license's permission, may have only one glass of wine during a meal.

D. In the salon bar the atmosphere is quieter and there are fewer people.

E. Children can go into pub gardens with their parents.

F. Pubs are an important part of British life.

G. British people like drinking beers in pubs.