为什么三国两晋南北朝时期科学技术和艺术成就能够领先世界，异彩纷呈？
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三国两晋南北朝时期是多民族国家 * * 分立与民族汇聚的时代，统治阶级为维护自身的统治，对科学技术给予一定的重视；民族融合为科技文化的发展融进了激情；中外交流为中国文化注入新的血液。所以这一时期的文化领先世界，异彩纷呈。
完形填空（共10小题，每小题1分，计10分） 阅读下面短文，掌握其大意，然后从各小题所给的四个选项中选出最佳选项。 Building a house is an operation which costs quite a lot of money．Suppose you plan to 46 a house，your first step is to find a suitable piece of 47 ，You will probably try to find a sunny place，in a 48 situation，near stores and bus stops，not too far from your friends and the place where you work． Next you will find an 49 builder．And together with the builder you will make a 50 ，The builder will draw it．The builder will also 51 the cost of your house．He will estimate(估计)the cost of the wood，the glass，and everything else that he must use in building the house．Later on，when he starts to build，this estimate must 52 ，because the prices may 53 ，and many other thing may happen between the time when he makes the estimate and the time when he builds the house． 54 the builder gives you his estimate，you may wish to change your plan．You may find that some of the things you wanted at first cost too much，or that you can 55 a little more and add something to your original plan．
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