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What does "pig out" mean in the eighth paragraph？
A．Sleep soundly.
B．Eat greedily.
C．Lie down.
D．Howl angrily.
答案
更多“What does "pig out" mean in the eighth paragraph？A．Sleep soundly.B．Eat greedily.C．Lie down”相关的问题
第1题
Dolly was once an awfully lonely sheep. When the famous cloned (of an exact copy of a plant or animal made by taking a cell from it and developing it artificially) animal made headlinesin 1997, she was the only mammal ever to be manufactured from the cell of an adult donor. Since then, the clone ranks have swelled, with mice and cattle also making their way out of the labs. Last week cloning technology took another step forward when an international biotechnology company announced that it had created a litter of five genetically identical piglets (young pigs), and that it had a pretty good idea of how they could one day be used as organ donors for ailing humans.
The idea of turning pigs into tissue factories has been around for at least 30 years. Pigs breed easily and mature quickly, and their organs are roughly the same size.as those of humans, meaning operations can be performed with a relative snap-out, snap-in simplicity. The problem is, once the donor organ is stitched in place, the body rebels, rejecting it even more violently than it would a human transplant. " A pig heart transplanted in a person would turn black within minutes, " says David Ayares, a research director with PPL Therapeutics, the biotech firm that helped clone Dolly and also produced the piglets.
What causes pig organs to be rejected so quickly is a sugar molecule on the surface of pig cells that identifies the tissue as unmistakably nonhuman. When the immune system spots this marker, it calls out its defenses. PPL scientists recently succeeded in finding the gene responsible for the sugar and knocking it out of the nucleus of a pig cell. Their next step would be to extract that nucleus, insert it into a pig ovum, and then into the womb of a host pig. The sugar free piglet that was eventually born could then be cloned over and over as a source of safe transplant organs. The idea is to arrive at the ideal animal and repeatedly copy it exactly as it is. The cloned piglets PPL introduced to the world last week were created in just this way, though for this first experiment in pig replication the scientists left the sugar genes intact.
Despite this recent success, PPL is not likely to be setting up its organ shop anytime soon. Knocking out the key sugar gene solves only the problem of short-term rejection. Much more has to be done before any solution to long-term rejection can be found. Nonetheless, Ayares is optimistic, insisting that pig organs could be available in as little as five years. For the present, even a little new transplant material is a big improvement over what's available, and for gravely ill patients awaiting a donor, that's no small thing.
What is true about Dolly according to the text？
A．She was a lonely sheep in the first place.
B．She was manufactured out of the lab.
C．She was cloned from the cell of a mature sheep.
D．She was replaced by cloned piglets in terms of importance.
第2题
Text 3
Dolly was once an awfully lonely sheep. When the famous cloned (of an exact copy of a plant or animal. made by taking a cell from it and developing it artificially) animal made headlines in 1997, she was the only mammal ever to be manufactured from the cell of an adult donor. Since then, the clone ranks have swelled, with mice and cattle also making their way out of the labs. Last week cloning technology took another step forward when an international biotechnology company an-nounced that it had created a litter of five genetically identical piglets (young pigs) , and that it had a pretty good idea of how they could one day be used: as organ donors for ailing humans.
The idea of turning pigs into tissue factories has been around for at least 30 years. Pigs breed easily and mature quickly, and their organs are roughly the same size as those of humans, meaning operations can be performed with a relative snap-out, snap-in simplicity. The problem is,once the donor organ is stitched in place, the body rebels, rejecting it even more violently than it would a human transplant. "A pig heart transplanted in a person would turn black within minutes," says David Ayares, a research director with PPL Therapeutics,the biotech firm that helped clone Dolly and also produced the piglets.
What causes pig organs to be rejected so quickly is a sugar molecule on the surface of pig cells that identifies the tissue as unmistakably nonhuman. When the immune system spots this marker, it calls out its defenses. PPL scientists recently succeeded in finding the gene responsible for the sugar and knocking it out of the nucleus of a pig cell. Their next step would be to extract that nucleus,insert it into a pig ovum, and then into the womb of a host pig. The sugar free piglet that was eventually born could then be cloned over and over as a source of safe transplant organs. The idea is to arrive at the ideal animal and repeatedly copy it exactly as it is. The cloned piglets PPL introduced to the world last week were created in just this way, though for this first experiment in pig replication the scientists left the sugar genes intact.
Despite this recent success, PPL is not likely to be setting up its organ shop anytime soon.
Knocking out the key sugar gene solves only the problem of short-term rejection. Much more has to be done before any solution to long-term rejection can be found. Nonetheless, Ayares is optimistic, insisting that pig organs could be available in as little as five years. For the present, even a little new transplant material is a big improvement over what's available, and for gravely ill patients awaiting a donor, that's no small thing.
51. What is true about Dolly according to the text？
[A] She was a lonely sheep in the first place.
[B ] She was manufactured out of the lab.
[C] She was cloned from the cell of a mature sheep.
[D] She was replaced by cloned piglets in terms of importance.
第3题
What does the man offer to do？
A．Track the package
B．Call the research department
C．Find out what happened
D．Bring the woman some keys
第4题
What does "out of sight and out of mind" (Line 2. Para. 1) probably mean？
第5题
What does the man mean？
A.He has refused another dinner appointment.
B.He doesn't eat out very often.
C.He knows the way to the restaurant.
D.He does not like to eat out either.
第6题
What does the underlined word "stifling " (Paragraph 1 ) probably mean？
A．Disappearing gradually.
B．Giving out into the air.
C．Hot and breathless.
D．Pleasing and comfortable.
第7题
What does the professor promise to do？
A．Pick out some books for her.
B．Tutor her himself.
C．Let her enroll in an easier course.
D．Ask another professor for his opinion.
第8题
What does the passage say about teenage boys and girls？
A．Only one out of four girls cries less often than boys.
B．Of four boys, only one cries very often.
C．Girls cry four times as often as boys.
D．Only one out of four babies doesn't cry often.
第9题
What does the writer think of the ads in the newspapers or magazines？
A．He believes what the ads said.
B．He thinks the ads must be very expensive.
C．He thinks the ads never turned out true.
第10题
For what purpose does the pilot shut off all the engines？
A．To find out exactly what happens.
B．To save fuel.
C．To fly more slowly.
D．To keep balance.
