听力原文： The stock market in New York has drifted up and down after comments from the chairman of the Federal Reserve Alan Greenspan who said the recent falls on the world market could be salutary in the long term. The market rose by more than 100 points in the first hour of trading, but fell back after Mr Greenspan's remarks. He told the congressional committee that the US economy should not be threatened by market problems in the Southeast Asia and said the economy was robust. Mr Greenspan said that even after the recovery on Wall Street, many investors were less wealthy than they had been a week ago. But it was a salutary event. The head of the US Central Bank implied that there had been an excessive optimism about the future of share prices and the recent decline might cool things down. If it hadn't been in Southeast Asia, something else would eventually have brought about this week's events. Mr Greenspan traced the origins of the Asian crisis in some details. There'd been an explosion in the flow of money into the region and this has helped fuel unsustainable property boom. Bank borrowed abroad and lent too much to the construction industry. When the project went sour, they had to meet their foreign currency borrowings with their own currencies devalued. The recent fluctuation of the stock market in New York was due to