The difficult case tested the ingenuity of even the most skillful physician.
A.credibility B.commitment C.honesty D.talent
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The difficult case tested the ingenuity of even the most skillful physician.
All experts agree that the most important consideration with diet drugs is carefully （ ）the risks and benefits.
It is time the nations of the world （ ）a halt to the manufacture of nuclear weapons.
As we can no longer wait for the delivery of our order, we have to （ ）it.
Children should avoid using mobile phones for all but essential calls because of possible health effects on young brains. This is one of the expected conclusions of an official government report to be published this week. The report is expected to call for the mobile phone industry to refrain from promoting phone use by children, and to start labeling phones with data on the amount of radiation they emit.The Independent Expert Group on Mobile Phones, chaired by former government chief scientist William Stewart, has spent eight months reviewing existing scientific evidence on all aspects of the health effects of using mobile phones. Its report is believed to conclude that because we don’t fully understand the nonthermal effects of radiation on human tissue, the government should adopt a precautionary approach ,particularly in relation to children.There is currently no evidence that mobile phones harm users or people living near transmitter masts. But some studies show that cell-phones operating at radiation levels within current safety limits do have some sort of biological effect on the brain.John Tattersall, a researcher on the health effects of radiation at the Defense Evaluation and Research Agency’s site at Porton Down, agrees that it might be wise to limit phone use by children. “If you have a developing nervous system, it’s known to be more susceptible to environmental insults,” he says, “so if phones did prove to be hazardous—which they haven’t yet—it would be sensible.”In 1998, Tattersall showed that radiation levels similar to those emitted by mobile phones could alter signals from brain cells in slices of rat brain, “what we’ve found is an effect, but we don’t know if it's hazardous,” he says.Alan Preece of the University of Bristol, who found last year that microwaves increase reaction times in test subjects, agreed that children's exposure would be greater. "There's a lot less tissue in the way, and the skill is thinner, so children’s heads are considerably closer,” he says.Stewart's report is likely to recommend that the current British safety standards on energy emissions from cell-phones should be cut to the level recommended by the International Commission on Non-Ionizing Radiation Protection, which is one-fifth of the current British limit. “The extra safety factor of five is somewhat arbitrary," says Michael Clark of the National Radiological Protection Board. “ But we accept that it’s difficult for the UK to have different standards from an international body. ”1.Just because it has not been confirmed yet whether mobile phone emissions can harm human tissue, according to the government report, does not mean that （ ）.2.Tattersall argues that it is wise to refrain mobile phone use by children in terms of （ ）.3.On the issue in question, Preece （ ）.4.What is w
The early pioneers had to （ ）many hardships to settle on the new land.
