题干

制作显微装片时,有些需要将细胞杀死,有些需要继续保持细胞活性,下列实验中,显微镜下观察到的仍是活细胞的是(  )

A:用吡罗红甲基绿染色剂显色的洋葱鳞片叶细胞

B:用健那绿显示线粒体的人口腔上皮细胞

C:置于清水中不发生质壁分离复原的洋葱鳞片叶表皮细胞

D:观察根尖分生区有丝分裂装片中处于分裂期的细胞

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答案(点此获取答案解析)

B

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完形填空

    The four famous rock stars were due to arrive at any moment and a large crowd of young people had gathered at the airport to welcome them.The police found it difficult to keep the crowd under1after the plane landed and the performers appeared.They smiled and waved2at everybody.Dressed in pink shirts and light blue trousers,and with their long hair and their musical instruments3their shoulders,the four young men looked very much4.

    In spite of the large number of policemen5,it was clear that the group would not be able to get to their waiting car6.Word had got out that they had written a new song which would be7when they performed at the grand hall that evening.They were now8with crying of “Play something! Play your new song!”

    Even the police looked9when the young men unfolded their instruments and prepared to do one of their numbers as the10for getting out of the airport.The crowd settled down and listened to the first11of the new song. As soon as it was over,there was a great burst of applause and then everyone started12and shouting like crazy. Several young women fainted and had to be carried away by the13unit which was standing by.Greedy for more, the crowd14a repeat performance.Once again the performers gave in,but when the crowd requested still another song,the group cheerfully but firmly15.

    Now closely surrounded by the police,they put away their16and stared towards their car which was some distance away.The crowd pushed forward,but the policemen,17arm in arm,prevented anyone from getting through. It took the singers a long time to reach their18.Finally,however,they got in and were just about to drive away when a young woman,who had19to get past the police,jumped onto the roof of the car.She shouted loudly as two policemen20her away and the car began moving slowly through the cheering crowd.