题干

关于物种的形成,下列叙述正确的是( )

A:生物进化过程中总是淘汰隐性性状

B:生物进化过程中总是淘汰显性性状

C:生物进化的实质是种群基因频率的改变

D:自然选择直接作用于不同的基因型,而不是表现型

上一题 下一题 0.0难度 选择题 更新时间:2019-09-08 10:43:57

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C

同类题4

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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.