题干

小明将一瓶薄塑料瓶装的饮料喝完后用瓶盖将瓶子密封,然后放入冰箱,一段时间后将其取出,发现瓶子变扁了,对于瓶内的空气,若不计分子势能,下列说法中正确的是 (   )

A:温度降低,压强增大

B:温度降低,压强减小

C:外界对其做功,内能增大

D:外界对其做功,内能减小

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答案(点此获取答案解析)

D

同类题3

       Fashions in child-care (儿童保育), as all parents know, come and go. Bottle-feeding or mother's milk?  Full-time parental care or a child-minder(儿童保育员)? These problems always trouble the parents a lot. And now, there is a book called Childsplay dealing with the problem of child-care.
     The author of Childsplay, Lucy Jackson, believes most school children do some sports at school. And many adults take regular exercise in their free time.
      Babies, though, spend most of the time in front of the television or sitting in a push-chair (折叠式婴儿车) or high chair. If the world were a safer place, every child would run around freely, but that is simply not possible. As a result, they become lazy, overweight and unfit.
     Ms. Jackson is worried that if small children take no regular exercise, bad habits will continue into adulthood (成人期 ). She suggests that parents should begin exercising with very small babies, moving their legs and arms gently in time to music. As children grow, they should follow and exercise program using soft balls, household furniture and play equipment.                                    
     Many experts in child development do not agree. They feel that children will learn to run and jump as they play naturally; they do not need planned exercise. They would not be overweight if they ate healthier food. An increasing number of parents, though, are taking their children to exercise classes. The kids jump around with their mothers to disco music.They seem to enjoy themselves, but it is not at all clear if the classes have any effect on their future development.