题目

科学家将含人的—抗胰蛋白酶基因的DNA片段注射到羊的受精卵中，由该受精卵发育成的羊能分泌含抗胰蛋白酶的奶。这一过程不涉及 A．DNA的自我复制 B．以DNA的一条链为模板合成RNA C．RNA的自我复制  D．按照RNA密码子的排列顺序合成蛋白质 答案：C15、He traveled to many mountain villages and saw many poor children out of school. This experience ______ his life. A. would change           B. had changed      C. was to change          D. was changing