题干

通过两年来生物课的学习,我们已经知道:地球上本来是没有生命的.从出现原始的生命到形成今天这样丰富多彩的生物界,是一个漫长的____过程.在这个过程中,许多物种灭绝了,新的物种又不断形成.达尔文的____对此作出了科学的解释.而经过学习动植物进化的大致历程,能够看出生物进化的总趋势是:____.

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答案(点此获取答案解析)

进化,自然选择学说,由简单到复杂、由低等到高等、由水生到陆生

同类题1

阅读短文,并将空格补充完整,使短文通顺,意思完整。(每空一词)

    A Little Horse Crossing the River

    There is an old horse and a little horse on a farm. One day the old horse asks the little horse to send the wheat to the mill(磨坊)。The little horse is very happy. He carries the wheat and runs toward the mill. But there is a river in front of the little horse. He stops and doesn't know ____ to do next. Just then Aunt Cow is passing by.

    The little horse ____,”Aunt Cow, please tell me. Can I cross the river?”

Aunt Cow answers.” It's not deep, you can cross it.”

    When the little horse begins to cross the river, a little squirrel(松鼠)shouts to him,” Little horse, don't cross it, you will be drowned. Yesterday ____ of my friends was drowned in this river.”

    The little horse is very ____ .Finally he ____ to go home and asks his mother.

    The old horse asks,”____ do you take the wheat back? What's wrong with you, my child?”

    The little horse answers sadly,” There is a river in front of me. Aunt Cow said it was not deep, but the little squirrel said it was deep. What shall I do?”

    The old horse says,” My child, you should try to cross the river by   7    . If you don't try, how do you know the river is deep or not.

    The little horse carries the wheat and    8      to the riverside. At last,he succeeds in   9    the river. Now, he knows    10    deep the river is.