何谓同质选配？异质选配？
参考答案：
同质选配是指选择具有相同优良性状和特点的优秀公、母羊来进行配种，目的是使双亲共同的优点在后代身上得到巩固和发扬光大。这种选配方式的特点是“以优配优”。
异质选配有两种情况，一种是选择具有不同优良性状和特点的优秀公、母羊来进行进行配种，目的在于使双亲的不同优良性状在后代身上得以结合，创造出一个新的类型；另一种是选择具有相同性状但优劣程度不同的公、母羊来配种，用公羊的优点来纠正或克服与配母羊的缺点或不足。这种选配方式的特点是“公优于母”。
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| Thomas Edison was American. He was a 1 scientist. He was born in 1847. When he was a child, he liked to find out how things 2 . He was in school for only three months. He asked his teacher a lot of 3 questions. Most of them had nothing to do 4 his lesson. The teacher thought the boy was not 5 and was not worth 6 . When he told this to Edison's mother, she took her son out of school. As she had been a teacher, she taught him 7 . The boy read a lot. Soon he became very 8 in sciene. 9 the age of ten Edison had already built a chemistry lab for himself. Ever since then, he never stopped 10 for new and better ways to do things. |
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