题目

Many Americans have found the cell phone valuable in providing help in emergencies and free time entertainment. 39.M________， it has also brought up 40.p________ in careless driving, irritating behaviors in public and high expenses. Cell phones are also 41.________ (流行的) in China, and many students own them. The question is 42.________ students should be allowed to use them at school. Some parents support it just for the need to communicate with their children, 43.w________ some others think it a bad idea, worrying that it will disturb usual educational 44.________ (环境). 近亲结婚后代患遗传病的可能性增大的原因是，血缘关系越近（        ） A．生活环境越相同          B．染色体数目越相同 C．遗传基因也越相似       D．生活习性越相同