题干

某学生发现他爸爸种植的水稻,生长迟缓,叶色发黄,茎杆不粗硬,易倒伏,学习化学后要他爸爸给水稻追加相应的复合肥料,你认为应选用的复合肥料是(  )

A:KNO3

B:NH4NO3

C:NH4H2PO4

D:K2SO4

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答案(点此获取答案解析)

A

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根据短文内容的理解,选择正确答案。

    We produce 500 billion of plastic bags in a year worldwide and they are thrown away polluting oceans, killing wildlife and getting dumped in landfills where they take up to 1,000 years to decompose. Researchers have been unsuccessfully looking for a solution.

    The 16-year-old Canadian high school student, Daniel Burd, from Waterloo Collegiate Institute, has discovered a way to make plastic bags degrade(降解) in as few as 3 months, a finding that won him first prize at the Canada Wide Science Fair, a $10,000 prize, a $20,000 scholarship, and a chance to revolutionize a major environmental issue.

    Burd's strategy was simple: Since plastic does eventually degrade, it must be eaten by microorganisms(微生物).If those microorganisms could be identified, we could put them to work eating the plastic much faster than under normal conditions.

    With this goal in mind, he grounded plastic bags into a powder and concocted(调制) a solution of household chemicals, yeast(酵母) and tap water to encourage microbes growth.Then he added the plastic powder and let the microbes work their magic for 3 months.Finally, he tested the resulting bacterial culture on plastic bags, exposing one plastic sample to dead bacteria as a control.Sure enough, the plastic exposed(暴露) to the live bacteria was 17% lighter than the control after six weeks.

    The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide.

    "Almost every week I have to do chores and when I open the closet door, I have piles of plastic bags falling on top of me.One day, I got tired of it and I wanted to know what other people are doing with these plastic bags.The answer: not much.So I decided to do something myself." Said Daniel Burd.