题干

将生长旺盛的某农作物植株培养在密闭、透时的玻璃钟罩内,在温度适宜恒定的条件下,测得晴朗的一昼夜钟罩内CO2浓度变化曲线如图所示,以下分析正确的是(    )

A:a﹣b段随着光照强度逐渐增加,光合作用速率不断提高

B:b﹣c段密闭钟罩中的CO2浓度低于大气中的CO2浓度

C:c﹣d段密闭罩内氧气含量充足,呼吸作用速率不断提高

D:d点后呼吸作用速率缓慢是因为温度较低而影响酶的活性

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答案(点此获取答案解析)

B

同类题5

阅读下列短文,从下面每小题的A、B、C、D四个选项中选出最佳选项

    Hershey chocolate is famous around the world. The man who began it, Milton Hershey, was glad to share the fruits of success with others.

    Milton Hershey was born on 13 September, 1857. In 1871, he started working for a local printer. But he didn't like this kind of work and ended the job quickly. Later, he helped make candy in a factory. After a few years, Milton knew that he was a good candy maker and he wanted to start his own candy business. In 1886, he started a caramel (焦糖) business, and four years later his business was very successful. After seeing how chocolate was made. Milton loved it right away. He got married and sold the caramel company for one million dollars and opened up a chocolate factory.

    Milton built a town with houses, schools, and stores so the workers in his factory could live nearby. As Milton made more money, he built a school for orphans (孤儿). When his wife died, Milton took all of his money and gave it to the school to help those children. He also set up the M. S. Hershey Foundation to help people get an education.

    Milton Hershey died in 1945, but the world remembers him for not only making chocolate, but for his work to help people. He is someone who built a town and helped people get jobs. He is someone who built a school for children who did not have families. He is someone who helped those who were sick and someone who made that chocolate, that delicious chocolate which most of us throughout me world enjoy.