题干

下列说法正确的是(   )

A:“用油膜法估测分子的大小”实验中油酸分子直径等于油酸溶液体积除以相应油酸膜的面积

B:载人飞船绕地球运动时容器内的水呈球形,这是因为液体表面具有收缩性的表现

C:运动小球在水平粗糙平面做减速运动停下后,不会自发地内能减小,动能增加而加速,是因为这违反了能量守恒定律

D:一定质量的理想气体经历等压膨胀过程,气体分子密度将减小、分子平均动能将增大

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答案(点此获取答案解析)

B,D

同类题1

阅读理解。

阅读短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

    Camping wild is a wonderful way to experience the natural world and, at its best, it makes little environmental influence. But with increasing numbers of people wanting to escape into the wilderness, it is becoming more and more important to camp unobtrusively(不引人注意地)and leave no mark.

    Wild camping is not permitted in many places, particularly in crowded lowland Britain. Wherever you are, find out about organizations responsible for managing wild spaces, and contact them to find out their policy on camping and shelter building. For example, it is fine to camp wild in remote parts of Scotland, but in England you must ask the landowner's permission, except in natural parks.

    Camping is about having relaxation, sleeping outdoors, experiencing bad weather, and making do without modern conveniences. A busy, fully-equipped campsite(野营地)seems to go against this, so seek out smaller, more remote places with easy access to open spaces and perhaps beaches. Better still, find a campsite with no road access: walking in makes a real adventure.

    Finding the right spot to camp is the first step to guaranteeing a good night's sleep. Choose a campsite with privacy and minimum(最小化的) influence on others and the environment. Try to use an area where people have obviously camped before rather than creating a new spot. When camping in woodland, avoid standing dead trees, which may fall on a windy night. Avoid animal runs and caves, and possible homes of biting insects. Make sure you have most protection on the windward side. If you make a fire, do so downwind of your shelter. Always consider what influence you might have on the natural world. Avoid damaging plants. A good campsite is found, not made—changing it should be unnecessary.