题目

下图表示有关遗传信息在细胞中传递的模拟实验，下列叙述合理的是 A．若X是RNA，Y是DNA，则试管内必须加入解旋酶 B．若X的碱基序列为CTTGTACAA，Y中含有U，则试管内必须加入逆转录酶 C．若X、Y都是DNA，则试管内必须加入核糖核苷酸 D．若X是mRNA，Y是蛋白质，则试管内还有其他种类的RNA 答案：D阅读理解       One day I went out and left my key at home. When I came back, I couldn't get in because my parents were away. I had to break a window, so I found a big stone(石头). There was a great noisewhen I broke the glass(玻璃), and I had to be careful when I reached through to turn the handle (把手). I was just climbing in when a deep voice said, "What are you doing?"       It was a policeman. My neighbor heard the breaking and telephoned the police.       It took me quite a long time to explain(解释) that I wasn't a thief (贼).1. One day the writer couldn't get into his house because       .A. he forgot to take his key with him and his parents weren't at homeB. his parents were staying with his uncleC. he left his key in his officeD. his parents were angry with him and didn't let him in2. The writer             with a big stone.A. broke the door      B. knocked at the doorC. broke the window   D. went away3. The writer heard a policeman's voice when he was             .A. turning the handle             B. breaking the doorC. climbing (爬) in through the window  D. knocking at the door4. Why did the policeman come?A. Because the writer wanted his help.B. Because the writer's neighbor telephoned the police.C. Because the writer phoned the police.D. Because the policeman heard the noise.5. At last the policeman knew that              .A. the writer was a thiefB. the writer's neighbor played a joke (玩笑) on himC. the writer's window is brokenD. the writer was the master (主人) of the house