题目

【A】Finally, we arrived in Loulan after several days of travelling. This (71) c            city was busy and (72) w            about 2,000 years ago. It was a stopping point on the famous Silk Road between the East and the West. It is (73) b            to have been gradually covered over by sandstorms from AD 200 to AD 400. I am so excited to be here! 【B】These are some of the Olympic athletes who have brought (74) j            to people across the world with their attempts to push the (75) b            of human achievement. We18．孟德尔通过豌豆杂交实验揭示了遗传的基本定律．下列相关叙述正确的是（　　）A．孟德尔遗传定律实质涉及的过程发生在有丝分裂中B．孟德尔巧妙设计的测交方法只能用于检测F1的基因型C．F2出现9：3：3：1性状分离比前提条件之一是各种基因型个体成活的机会相等D．F1形成配子时，产生了数量相等的雌雄配子，各种雌、雄配子结合的机会相等