Weproduce500billionofplasticbagsinayearworldwideandthey...

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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.

7. Daniel Burd won first prize at the Canada-Wide Science Fair because .

A. he found a way to degrade plastics in shorter time. B. he contributed much to environmental protection.

C. he found a new kind of microorganism. D. he could encourage microbe growth in an easier way.

8．Daniel Burd exposed one plastic sample to dead bacteria to .

A. make the live bacteria work better. B. know which bacteria worked faster.

C. test how effective his method was. D. control the temperature in the process.

9. Maintaining the required temperature takes little energy because .

A. plastics can get hot easily. B. microbes can produce heat themselves.

C. much carbon dioxide is produced. D. the temperature can be controlled.

10. Daniel Burd got his idea from .

A. his school textbook. B. the failure of researchers.

C. his everyday work. D. the practice of other people.