MBA每日一练（2019/1/19）_网考网(Netkao.com)

MBA每日一练（2019/1/19）

第1题：|x+2|+|x-8|＜a的全部解集是空集．
(1)a=10；(2)a≤1．

【分析题】：

For the first time, stem cells purified from fat have been used to heal an injury in a living animal. Michael Longaker of Stanford University inCalifornia and his team showed in mouse experiments that so-called adipose derived adult stromalADAS) cells purified from a rodent’s belly fat could be coaxed to heal a skull fracture too large to mend by itself.
The power ofADAS cells to transform into bone, cartilage and even neurons has been studied for years in test tubes.But Jeffrey Gimble, who studies humanADAS cells at Louisiana State University inBaton Rouge says Longaker’s report is an important step forwarD、"Actually repairing a defect in an animal model had never been done. This is an excellent study." If the same technique works in humans, these cells could be coaxed to mend broken bones and correct other defects in tens of thousands of surgical procedures each year in which bone grafts and prosthetics are now necessary.
Longaker’s group tested the ability ofADAS cells to heal four-millimetre-long fractures surgically-induced in the skulls of mice. In 12 weeks, the cells filled 70 to 90 per cent of the defects, while untreated animals had only unorganized bone formation in less than 10 per cent of the fractures. No extreme genetic manipulation or treatment of the cells was necessary.ADAS cells began manufacturing bone when they were simply laid onto a biodegradable polymer that contained apatite, a compound that naturally occurs in bone. Furthermore, theADAS cells performed as well as bone marrow stromal cells, which would seem to be more natural architects of bone. It remains to be seen whether humanADAS cells will build bone as effectively.But researchers are excited about the prospects. Human bone marrow stromal cells are already being used in clinical trials as sources of skeleton-building material, but theADAS cells may have some significant advantages.
Longaker reports thatADAS cells grow seven times faster than the bone marrow cells in the laboratory.And it is relatively easy to harvest more than a litre of fat tissue, even from patients who are not obese.Bone marrow is much less plentiful and must be removed in a painful surgical procedure. Of course, liposuction itself is not a pleasant operation.But according to theAmerican Society of Plastic Surgeons, more than 300,000 people volunteered to have the procedure in 2003 simply for cosmetic reasons. "If the procedure was the first step to healing broken bones or replacing other tissue its popularity could only grow," says Gimble. "Just think of that."

第2题：
{{B}}Directions:{{/B}}
Read the following four passages.Answer the questions below each passage by choosingA,B,C、orD、Mark your answers onANSWER SHEET 1.
{{B}}Passage One{{/B}}

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