2021年高考英語難點37講--難點23 有章可循的主旨大意題
“the cornea(角膜)is like a five-layered sandwich”,says raymond curran,a doctor from omagh,northern ireland.“once the bacteria get into a layer they can reproduce there and turn the cornea opaque(too dark to see through).”
an optician(驗光師）may see one possibly sight-threatening case each month,but at an eye hospital there may be several each week.acanthamoeba,often seemingly mild,can be misjudged until it is too late.meanwhile,pseudomonas,more seriously,can cause increasing sight loss with each hour that passes.if not treated immediately,patients may need a corneal replacement.
and the really bad news,according to professor roger buckley,at the moorfields eye hospital in london,is that acanthamoeba is“one of the hardest germs on earth”——it can survive in antarctica.
question 2:in the passage the writer mainly wants to tell us ________.
a.the possible danger of contacts
b.the importance of keeping contacts clean
c.some doctors’ opinions about contacts
d.the advantages and disadvantages of contacts
3.()with only about1000 pandas left in the world，china is desperately trying to clone(克隆) the animal and save the endangered species(物種).that’s a move similar to what a texas a＆m university researchers have been undertaking for the past five years in a project called “noah’s ark”.
noah’s ark is aimed at collecting eggs，embryos(胚胎)，semen and dna of endangered animals and storing them in liquid nitrogen.if certain species should become extinct，dr.duane kraemer，a professor in texas a＆m’s college of veterinary medicine，says there would be enough of the basic building blocks to reintroduce the species in the future.
it is estimated that as many as 2 000 species of mammals，birds and reptiles will become extinct in over 100 years.the panda，native only to china，is in danger of becoming extinct in the next 25 years.
this week，chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a japanese white rabbit.they are now trying to implant the embryo into a host animal.
the entire procedure could take from three to five years to complete.
“the nuclear transfer（核子移植)of one species to another is not easy，and the lack of available （capable of being used）panda eggs could be a major problem.”kraemer believes.“they will probably have to do several hundred transfers to result in one pregnancy （having a baby）.it takes a long time and it’s difficult，but this could be groundbreaking science if it works.they are certainly not putting any live pandas at risk，so it is worth the effort，”adds kraemer，who is one of the leaders of the project at texas a＆m，the first-ever attempt at cloning a dog.