题目

采用基因工程的方法培育抗虫棉，下列导入目的基因的作法正确的是（ ）                     ①将毒素蛋白注射到棉受精卵中                                                               ②将编码毒素蛋白的DNA序列，注射到棉受精卵中                                        ③将编码毒素蛋白的DNA序列，与质粒重组，导入细菌，用该细菌感染棉的体细胞，在进行组织培养          Once upon a time, there was a beautiful bird, which was very curious about hell. When she was little, her mother always told her that if she didn’t master the flying skills, she would go to hell. She was so curious about hell that she always asked others what hell looked like, but no one was sure, because none of them had ever been there. Some said hell was a place full of water, and others told her that hell was full of burning fire. However, the bird knew they were lying. She wanted to find out what hell was.When other birds were learning flying skills, she always hid herself and watched them. She thought in this way she could go to hell and see what hell looked like. However, she spent so little time learning flying skills that one day she was caught by a little boy. The little boy gave her to his grandpa in the countryside as a gift. The old man liked her very much. He made a delicate cage and put her in it. The bird was very worried because she thought she couldn’t find out what hell was like staying in this small cage. However, she couldn’t escape. Day after day, she just stayed in the cage, watching other birds flying. She lost her freedom and she became sadder and sadder. At last, she became ill. The old man finally opened the cage, but she was too weak to fly. Lying no the ground, she thought of the question that she ever asked all the time.“What does hell look like?”“Hell is a small well-decorated cage.” Before she closed her eyes forever, she finally answered that question herself.【小题1】What does the underlined word “master” in the first paragraph mean?A．Miss.B．Finish.C．Follow.D．Learn well.【小题2】Why did the bird hide herself when other birds were learning flying skills?A．Because she was lazy.B．Because she didn’t like learning flying skills.C．Because she thought she could go to hell by doing this.D．Because she thought she didn’t have to learn flying skills.【小题3】According to the passage, the bird at last found that     .A．hell was a place full of water.B．hell was a place full of burning fireC．there was no hellD．hell was a small well-decorated cage