82.Why is OC-17 of vital importance to the creation of a shell? (No more than 15 words)

　 We must act for a better tomorrow as soon as possible.

SECTION B

　 Directions: Answer the questions according to the information given in the passage and the required words limit.

　It has been the scientific mystery for centuries---until now, that is. Scientists have solved the

problem of whether the chicken or the egg came first. The answer, they say, is the chicken.

　 Researchers found that the fomation of egg shells relies on a protein found only inside a

chicken . Therefore, an egg can exist only if it has been inside a chicken. The protein, called

OC-17, acts to speed up the development of the shell. This hard shell is essential to house the

yolk(卵黄) and its protective liquid while the unborn chicken develops inside.

　 Scientists from Sheffield and Warwick universities used a supper computer to examine the

formation of an egg. The computer revealed that OC-17 is crucial in starting　 the early

stages of the creation of a shell. The protein changes calcium carbonate(碳酸钙) into calcite

crystals(方解石)and it is calcite crystals that make up the shell. Calcite crystals are found in

many bones and shells but chickens form them faster than any other species---creating six

grams of shell every 24 hours.

Dr Colin Freeman from Sheffield university said, “It had long been suspected that the egg

came first but now we have the scientific evidence that shows that in fact the chicken came first. The protein had been identified before and it was linked　 to egg formation but by examining it closely we have been able to see how it controls the process.”

　Professor John harding, from the same university, said the discovery could have other uses.

“Understanding how chickens make egg shells is fascinating in itself but can also give directions towards designing new materials and processes,”he said. “Nature has found creative solutions that work for all kinds of problems in materials science and technology----we can learn a lot from them.”

81.What is OC-17 mentioned in the passage? (No more than 12 words)

_______________________________________________________________________________

　 .plant trees

　 .avoid_____78_____such as paper and water

　 .spread awareness about these simple ways to save the planet to_____79_____

　 .reduce, reuse and recycle

　 ._____74____

　 ._____75_____instead of using of a vehicle

　 .take shorter showers

　 ._____76_____which are environment friendly

　 It seems unimportant for individuals to_____73______,but together they can have a strong effect.