题干

20世纪90年代,乌干达薯业遭到了病毒的毁灭性打击.科学家研究其原因发现,是一种新的病毒引发的疾病,而这种新病毒是由两种已知病毒重组产生的,这一事实有力地支持了下列哪一观点(    )

A:转基因生物有可能成为新的入侵物种,威胁生态系统中的其他生物的生存

B:导入转基因生物的外源基因有可能与感染转基因生物的某些病菌或病原体杂交,从而组装出对人类或其他生物有害的病原体

C:转基因植物的抗除草剂基因,有可能通过花粉传播而进入杂草中,使杂草成为除不掉的“超级杂草”

D:抗虫棉能抵抗棉铃虫,但随着棉铃虫抗性增强,抗虫棉有可能被淘汰

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B

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    What's going on under Liverpool?
A Rainy Day in Liverpool

    Dark clouds appear over the River Mersey and a cold wind is blowing. A few rain drops are beginning to fall. We're in the famous city of Liverpool and we're going to spend this rainy day in the Williamson Tunnels.
  An Interesting Life Story

    Joseph Williamson was born into a poor family in 1769,but left home and went to work for a tobacco company aged 11. He began at the bottom, and finally became head of the business.

 An Unsolved Mystery

    Nobody knows why Williamson dug tunnels under most of Liverpool, but many think it was to create jobs. Perhaps half of Liverpool's population worked for him. The industry of war had made enormous amounts of money, but now Liverpool was in a terrible financial situation.

 The King of Edge Hill

    I went on a guided tour starting close to where his empire began in Edge Hill. In the tunnels, the steps leading from rooms below ground to those buildings, which no longer exist, seem particularly ghostly.

Incredible Engineering

    We go into the Double Tunnel. It's just been discovered that it's actually a triple tunnel - but nobody knows why the three tunnels were built on top of each other.

    We finish the tour and decide we'll have a coffee in the Williamson Tunnels Cafe Bar. There, I notice lots of flyers for bands and theater groups that are coming to play there.

Why Liverpool?

    Apart from the obvious attractions like the football clubs, or anything to do with the Beatles, Liverpool has a lot to offer. Princes Park and Croxteth Park were royal hunting grounds and the trees are 200 years old. Renshaw Street displays are an unusual mix of architecture styles. The nightlife is exciting. If you want to experience a part of the British Isles with a character entirely different from London, you should definitely come to Liverpool.