题目

下列变异的原理一般认为属于基因重组的是 A．将转基因的四倍体与正常的二倍体杂交，生产出不育的转基因三倍体鱼苗 B．血红蛋白氨基酸排列顺序发生改变，导致某些贫血病 C．一对表现型正常的夫妇，生下了一个既白化又色盲的儿子 D．目的基因被误插入受体基因的非编码区，使受体基因不能表达 答案：CMr.Johnson is a hardworking teacher. Every day, he spends too much time with his work. With little sleep and hardly any break, so he works from morning till night. Hard work have made him very ill.“He has ruined his healthy. We are worried about him.” That is which other teachers say. Yesterday afternoon. I paid visit to Mr. Johnson. I was eager to see him, but outside her room I stopped.I had to calm myself down. Quietly I step into the room. I saw him lying in bed, looking at some of the picture we had taken together. I understood that he missed us just as many as we missed him.