Many workers who worked in the World Trade Center after the September eleventh attacks became sick. They breathed a mix of dust, smoke and chemicals in the ruins of the Twin Towers and a third building that fell. Some went clays without good protection for their lungs. Five years later, many of the thousands who worked at Ground Zero in the early days after the attacks still have health problems.

　　Doctors at Mount Sinai Medical Center in New York City have announced the results of the largest study of these workers. The study confirmed high rates of breathing problems in members of the building trades, firefighters, police officers and other workers. Almost seventy percent of the workers in the study had a new or worsened breathing problem. These problems developed during or after their time working in the mountain of wreckage. About sixty percent still had breathing problems at the time of their examination. The researchers say they decided to study the effects on breathing first because other disorders might be slower to appear. Mount Sinai says it tested almost twelve thousand people between two thousand two and two thousand four. Eight out of ten of them agreed to have their results used in the report. The new results added strength to a Mount Sinai study released in two thousand four. That study was based on only about one thousand workers.

　　Some lawmakers have sharply criticized city and state officials for letting workers labor at Ground Zero without satisfactory equipment. Officials have also been criticized for saying the air was relatively safe. State and federal officials have promised more than fifty million dollars to pay for treatment of the workers. Doctor Robin Herbert is one of the directors of the Mount Sinai testing program. She says people are still coming to the hospital for treatment of problems that were caused by the dust at Ground Zero. In her words:" My worry is that money will be gone in a year, and what happens then?"

　　47. What contributed to problems of the workers in World Trade Center after the attacks?

　　48. Who had the most serious breathing problems according to the latest study?

　　49. The researchers decided to carry on some study on the effects on breathing first because __________ might appear in a later period of time.

　　50. ______ are sharply criticized by some lawmakers because they let workers labor at Ground Zero with out satisfactory equipment.

　　51. What measures have the officials promised to take to deal with the health problem?

　　答案47. A harmful mix of dust，smoke and chemicals in the ruins.

　　48. The building trades，firefighters，police officers and other workers. 49. other disorders

　　50. City and state officials 51. To pay more than fifty million dollars for treatment of the workers.