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提问人：网友apollon_hhy
发布时间：2022-01-07
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LED materials include direct and indirect bandgap ones.
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更多“LED materials include direct and indirect bandgap ones.”相关的问题
第2题
The order processing is most exactly expressed as ( ) in sequence.
A、Take order in a standardized form è confirm the order è internally distribute the order form è communicate with the customer
B、Take order in a standardized form è internally distribute the order form è confirm the order è communicate with the customer
C、Internally distribute the order form è take order in a standardized form è communicate with the customer è confirm the order
D、Communicate with the customer è take order in a standardized form è internally distribute the order form è confirm the order
第3题
？Read the text below about a management training course．
？In most of the lines(41-52)there is one extra word．It is either grammatically incorrect or does not fin with the sense of the text．Some lines，however，are correct．
？If a line is correct，write CORRECT on your Answer Sheet．
？If there is an extra word in the Iine，write the extra word in CAPITAL LETTERS on your Answer Sheet
Managing-the human side of many enterprise-today calls for top-level talents in
42．self-management and the management of others and this type course offers the inside
43．track to gaining skills which needed to achieve outstanding effectiveness．It is designed
44．for executives at all levels，to strengthen core skills in the areas of management
45．and communication skills．By the end of the course，individuals will have been taken a
46．major step forward in their ability to achieve truly excellent levels of performance，
47．from themselves and others．To maintain a high level of stimulation throughout course，
48．a variety of learning methods will be employed．These include formal lectures．
49．team exercises and case studies All will be carefully managed to ensure you that
50．learning is developed through relating to each one individual’S own work experiences．
51 In order to ensure that each participant derives the maximum of benefit from
52 the course，numbers are l imited to 15．So don't delay-book your place now！
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第4题
| 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 1000 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(分解) 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 ground 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 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. 小题1:Daniel Burd won first prize at the Canada－Wide Science Fair because________.
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第5题
Some of the internally generated light suffers total internal reflection (TIR) at the semiconductor/air interface and cannot be emitted into the outside.
第6题
Free space wavelength coverage by different LED materials from the visible spectrum to the infrared including wavelengths used in optical communications.
