题型:阅读理解 题类:真题 难易度:普通
2012年高考英语真题试卷(湖南卷)
Harvard researchers have created a tough, low-cost, biodegradable (可生物降解的) material inspired by insects' hard outer shells. The material's inventors say it has a number of possible uses and someday could provide a more environmentally friendly alternative to plastic. The material, made from shrimp ('虾) shells and proteins produced from silk, is called "shrilk." It is thin, clear, flexible and strong.
A major benefit of the material is its biodegradability. Plastic's toughness and flexibility represented a revolution in materials science during the 1950s and '60s. Decades later, however, plastic's very durability (耐用性) is raising questions about how appropriate it is for one-time products such as plastic bags, or short-lived consumer goods, used in the home for a few years and then cast into a landfill where they will degrade for centuries. What is the point of making something that lasts 1,000 years?
Shrilk not only will degrade in a landfill, but its basic components are used as fertilizer(肥料), and so will enrich the soil.
Shrilk has great potential, the inventors said. Materials from which it is made are plentiful in nature, found in everything ranging from shrimp shells, insect bodies to living plants. That makes shrilk low cost, and its mass production possible should it be used for products demanding a lot of material.
Work on shrilk is continuing in the lab. The inventors said the material becomes flexible when wet, so they're exploring ways to use it in wet environments. They're also developing simpler production processes, which could be used for non-medical products, like for computer cases and other products inside the home. They're even exploring combining it with other materials, like carbon fibers, to give it new properties.
Taking a math test can be pretty stressful. Even if you know the material, you can still get the problem wrong. Knowing how to go through your math test and check your work can save you from handing in a test full of mistakes that can be avoided. {#blank#}1{#/blank#}
Write it out
You can also check a math problem by writing everything out on paper. {#blank#}2{#/blank#} Writing out math problems reduces your chances of missing anything to the lowest possible level, which is a common cause of incorrect answers.
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Make sure your answers work by doing the opposite procedure of what your problem calls for, including the answer you got the first time around. In other words, you would use the opposite of this addition problem—subtraction (减法)—to determine whether or not your answer is the correct one.
Plugging in
You may find that a variable isn't good enough or have a problem where you have to solve for a variable (变量). {#blank#}4{#/blank#} This is the only real way to assure yourself that the answer you've found is correct.
Check for a reasonable answer
{#blank#}5{#/blank#} For example, if you get an answer in the millions and you know it should be in the thousands, you've likely misplaced a point. Go back through the work on your paper to make sure all of your formulas and calculations are correct. If everything looks okay, do the problem again and compare the result of the second try to what you've got on the first try.
A. Do the opposite B. Correct the answers C. Plug the variable in the equation (方程) to check it out. D. Therefore you'll improve your grades, as well as your math skills. E. It also helps you to figure out everything after you have already finished the test. F. If the result of a problem seems to make no sense, it indicates that the answer is incorrect. G. This helps you to know what information you have and what information you need to solve. |
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