题目

如下图所示，肺炎双球菌转化实验中，在培养有R型细菌的A、B、C、D四支试管中，一次分别加入从S型细菌中提取的DNA、DNA和DNA酶、蛋白质、多糖，经过培养，检查结果发现有R型细菌转化的是    答案：A阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。I found out one time that doing a favor for someone could get you into a lot of trouble. I was in the eighth grade at the time, and we were having a final test. During the test, the girl sitting next to me whispered something, but I didn’t understand. So I leaned over her way and found out that she was trying to ask me if I had an extra pen. She showed me that hers was out of ink and would not write. I happened to have an extra one, so I took it out of my pocket and put it on her desk.Later, after the test papers had been turned in, the teacher asked me to stay in the room when all the other students were dismissed. As soon as we were alone she began to talk to me about what it meant to grow up; she talked about how important it was to stand on your own two feet and be responsible for your own acts. For a long time, she talked about honesty and emphasized the fact that when people do something dishonest, they are really cheating themselves. She made me promise that I would think seriously（认真地） about all the things she had said, and then she told me I could leave. I walked out of the room wondering why she had chosen to talk to me about all those things.Later on, I found out that she thought I had cheated on the test. When she saw me lean over to talk to the girl next to me, it looked as if I was copying answers from the girl’s test paper. I tried to explain about the pen, but all she could say was it seemed very very strange to her that I hadn’t talked of anything about the pen the day she talked to me right after the test. Even if I tried to explain that I was just doing the girl a favor by letting her use my pen, I am sure she continued to believe that I had cheated on the test.1.The girl wanted to borrow a pen, because ____________ .A. she had not brought a pen with herB. she had lost her own on her way to schoolC. there was something wrong with her ownD. her own had been taken away by someone2.The thing(s) emphasized in her talk was(were) ____________ .A. honesty B. sense of dutyC. seriousness D. all of the above3.The boy knew everything ____________ .A. the moment he was asked to stay behindB. when the teacher started talking about honestyC. only some time laterD. when he was walking out of the room