题目

现代生物进化理论认为,生物进化的实质是种群基因频率的改变。下列可以定向地改变种群的基因频率的是( )。 A.基因突变      B.基因重组 C.自然选择        D.迁移 答案：C 【解析】基因突变和基因重组具有不定向性,都是可遗传的变异,但它们仅仅是选择的原材料,其中基因重组不能改变种群的基因频率。种群中如果含A基因的个体比含a基因的个体更多地迁移到另一个地区,这个种群中A基因和a基因的频率就会发生相应的变化,但不会定向地改变种群的基因频率。自然选择则It was only a few weeks after my surgery, and I went to Dr. Belt's office for a checkup. It was just after my first chemotherapy（化学疗法） treatment. My scar was still very tender. My arm was numb underneath. As usual, I was taken to an examination room to have my blood drawn, again —a terrifying process for me, since I'm so frightened of needles.I lay down on the examining table. Ramona entered the room. Her warm smile was familiar, and stood out in contrast to my fears.  She knew about my fear of needles, and she kindly hid the equipment under a magazine. As we opened the blouse, the fresh scar on my chest could be seen.She said, “How is your scar healing?”I said, “I think pretty well. I wash around it gently each day.” The memory of the shower water hitting my numb chest flashed across my face.She gently reached over and ran her hand across the scar, examining the smoothness of the healing skin and looking for any irregularities. I began to cry gently and quietly. She brought her warm eyes to mine and said, “You haven't touched it yet, have you?” And I said, “No.”So this wonderful, warm woman laid the hand on my chest and she gently held it there. For a long time, I continued to cry quietly. In soft tones she said, “This is part of your body. This is you. It's okay to touch it.” But I couldn't. So she touched it for me. The scar. The healing wound. And beneath it, she touched my heart. Then Ramona said, “I'll hold your hand while you touch it.” So she placed her hand next to mine, and we both were quiet. That was the gift that Ramona gave me.【小题1】After I got my first chemotherapy treatment, _________.A．I began to feel betterB．my scar was still painfulC．I could hardly stretch my armD．I got tired of operation【小题2】Ramona hid the equipment under a magazine to _________.A．cheer me upB．rid my fearC．make me amused D．tease me【小题3】 When Ramona examined my healing skin, __________.A．she was carelessB．she hurt meC．I started to cryD．she was in tears【小题4】I began to have the courage to touch the scar _________.A．because of Ramona’s encouragementB．because I could face the factC．because of Ramona’s gentlenessD．because Ramona and I became friends【小题5】What is the author’s attitude towards Ramona?A．Objective B．GratefulC．DoubtfulD．Helpless