题干

下图是获得抗虫棉的技术流程示意图。卡那霉素抗性基因(kanr)常作为标记基因,只有含卡那霉素抗性基因的细胞才能在卡那霉素培养基上生长。下列叙述正确的是(  )

A:构建重组质粒过程中需要限制性内切酶和DNA连接酶

B:愈伤组织的分化产生了不同基因型的植株

C:卡那霉素抗性基因(kanr)中有该过程所利用的限制性内切酶的识别位点

D:抗虫棉有性生殖后代都能保持抗虫性状的稳定遗传

上一题 下一题 0.0难度 选择题 更新时间:2014-10-10 12:25:15

答案(点此获取答案解析)

A

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短文续写

    In 1989, fresh out of high school, I had the difficult task of choosing a career path before college started in three months. In those days in Pakistan, there were limited options (选择): becoming a doctor or an engineer, or entering the financial world after getting a business degree. I wasn't interested in engineering, so that I was left with medicine or business. I couldn't decide.

    My uncle, one of the ciders in the family, suggested that I do a work placement to experience it for a month in an international company followed by a month in a hospital. After that, I could make a decision. It seemed like a brilliant idea.

    I was accepted for a month's placement at a foreign bank in Karachi. I got a feel for how the world of finance functioned, made new friends, and generally enjoyed the mostly easy-going work surroundings.

    The month passed rapidly, and soon I began working at a leading hospital in Karachi. The experience couldn't have been more different. The hospital had an intense (紧张的) environment. The days started early (at 7 am, compared to 9 am at the bank), and were filled with endless duties. And the night calls! This was crazy, working all day, through the night, and again the next day.

    I began thinking about my two experiences. The bank had offered a more relaxing atmosphere, better working hours and less stress. The hospital was full of excitement and unpredictability, but the studying and training was difficult. It seemed that the business option was going to win out.

    Near the end of my month at the hospital, I was driving home after an especially busy night call. In front of me was a public bus, with college students sitting on the top. As the driver weaved through (穿梭) traffic, I could see the boys shaking from side to side.

注意:⒈所续写短文的词数应为150词左右;

⒉应使用5个以上短文中标有下划线的关键词语;

⒊续写部分分为两段,每段的开头语已为你写好;

⒋续写完成后,请用下划线标出你所使用的关键词语。

Paragraph 1: Suddenly, a boy fell off the back of the bus.        ▲              .

Paragraph 2: The next day, when I went to hospital to see the boy, all his family got up, with grateful smiles on their faces.            ▲                   .