听力原文： The World Health Organization says extraordinary progress has been made since the global campaign to eradicate polio was launched in 1988. At that time, it says, 350 thousand children a year were paralyzed from this crippling disease. It says this figure dropped to 35 hundred last year. W-H-O Coordinator for the Global Polio Eradication Initiative, Bruce Aylward, says last year a record 550 million children under age five were immunized in 82 countries against polio. Although this is an important achievement, he says the job is not yet over. 'The major challenge right now is to stop polio transmission everywhere within the next 24 months so that we can certify the world polio free on time in 2005. The greatest challenge to doing that will be making sure we access every child in the big remaining, heavily endemic or heavily infected polio areas.' The World Health Organization says the polio virus is now present in no more than 20 countries. This is down from 125 in 1988. But, it notes immunizing children in these few remaining countries will not be easy. W-H-O says major difficulties lie in war-torn countries such as Afghanistan, Angola, the Democratic Republic of Congo, Somalia, and Sudan. But, it says problems also exist in polio-endemic countries such as Nigeria, Ethiopia, Pakistan, and Northern India. W-H-O vaccine export, Bjorn Melgaard says the goal is to be able to eventually stop immunizing children against polio. 'Once we are absolutely certain that the virus is not spreading that epidemics can no longer occur, that the containment has been achieved, then we can stop vaccination.' Dr. Melgaard adds that the benefits from eradicating polio will be enormous. Besides ending the human suffering, he says countries will save about one-and-haft billion dollars a year in immunization costs. But the World Health Organization warns against complacency. It says the whole world is at risk of polio until the last polio virus is eradicated. This means everyone will have to remain vigilant and committed to achieving this major public health goal. Questions: 23.According to WHO coordinator, how soon shall we stop polio transmission everywhere so as to make the world polio free on time in 2005? 24.How many countries did they haste the polio virus in 1988? 25.What are the war-torn countries that WHO says major difficulties lie in? 26.What is the goal of this campaign? (43)