题干

如图所示是某同学做的一个实验,先在甲瓶底部铺层砂子(如图甲),然后放入点燃浸过酒精的棉花(如图乙);再用剥了壳的熟鸡蛋堵住瓶口(如图丙),过一会儿可看到什么现象,请解释其原因?

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答:现象:鸡蛋会被吸入瓶子.

因为酒精在燃烧过程中,瓶中的空气受热膨胀体积变大,会被挤出瓶子一部分.当酒精燃烧完之后用剥壳的熟鸡蛋堵住瓶口时,瓶内气体温度降低,气压减小,而瓶外气压不变,瓶外大气压着鸡蛋进入瓶中.

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    There's no doubt that our character has a profound effect on ourfuture. What we must remember, however, is not merely how powerful character isin influencing our fate (命运), but how powerful we are in shaping our own character and, therefore, our own fate. Character may determine our fate, but character is not determined by fate.

    It's a common mistake to think of character as something that is fully formed and fixed very early in life. It calls to mind old proverbs like“A leopard can't change its spots” and “You can't teach an old dog new tricks.”

    This perspective that our character is “etched in stone” is supported by a great deal of modern psychology emphasizing self-acceptance. As Popeye says, “I am what I am.” The hidden message is: Don't expect me to bemore, better, or different.

    Ultimately, these views of humanity totally under value the lifelong potential for growth that comes with the power of reflection and choice.

    How depressing it would be to believe that we can't choose to be better, more honest, more respectful, more responsible, and more caring. Noneof us should give up the personal seeking to improve our character. Not because we're bad, we don't have to be sick to get better, but because we're not asgood as we could be.

    There are so many things in life we can't control, whether we're beautiful or smart, whether we had good parents or bad, whether we grew up with affirmation or negation. It's inspiring to remember that nothing but moral willpower is needed to make us better.

    No, it isn't easy. But if we make a great effort to become moreaware of the habits of heart and mind that drive our behavior, we can begin to place new emphasis on our higher values so that we become what we want our children to think we are.