题干

从分子水平上对生物体具有多样性或特异性的分析,错误的是(    )

A:碱基对的排列顺序的千变万化,构成了DNA分子的多样性

B:碱基对的特定的排列顺序,又构成了每一个DNA分子的特异性

C:一个含2000个碱基的DNA分子,其碱基对可能的排列方式就有41000

D:某DNA片段由1700个碱基对组成,其碱基对可能的配对方式有41700

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答案(点此获取答案解析)

D

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        Around four years ago, I received a call from the principal of our school as to the “Parents View” talk the next morning. He asked me to speak to the group. After the call, my whole body became feverish and panicky. The time from his call to the next morning seemed like years. The whole night, I could not sleep with many ominous_apprehensions in mind. One of them was to call the principal with regret and tell him that I could not come. Finally, I gathered some courage. I thought, “If I miss this opportunity, surely the school will never invite me again to any of their programs.”

        I reached the school in time. Before my turn came, my whole body was trembling. When my turn came and I started speaking, my heartbeat increased and my mouth went dry. I wasn't even able to read the written speech properly. I was not aware of where I was standing and what I was reading. That was the day when I realized my biggest weakness, Public Speaking.

         After my speech, I met with the principal and explained what happened to me. He told me that this happens to everyone. Even great speaker, faced the same things when they started. He suggested that I come again next time.

         Around one month later, I was invited to refer to a topic on Motivation. This time I was feeling comfortable. My speech was not only appreciated by the principal as well as the teachers, because I was able to get my idea across to them. They encouraged and praised my efforts.

         After delivering this presentation successfully, I became more confident. I said to myself, “If I can speak in front of such a learned audience, like the principal who educates others, I can now speak in front of others too.”

         I started delivering lectures in my plant, on various topics like Self Motivation, Personality Development, Personal Excellence, Spoken English and Presentation Skills. This has become a passion for me. I learned that everything is possible if we have the courage to take the first step.