BUKHANNON, West Virginia—Two rescue teams slowly moved along a two-mile path on Monday night to the site of a coal mine explosion that trapped 13 miners, who had not been heard from since the early morning accident. Meanwhile, at a nearby church, more than 250 family members and friends gathered, waiting for updates（最新报道）on the rescuers’ progress. The miners were trapped at about 6:30 and many families weren’t informed of the accident until about 10 a.m-more than three hours after it happened. “It’s very upsetting, but you’ve got to be patient, I guess,” said John Helms, whose brother, Terry, was trapped in the mine. The trapped miners were about 260 feet underground and about 10,000 feet from the Sago Mine’s entrance, said Roger Nicholson, general counsel from International Coal Group. At a late night news conference, Nicholson said one team had advanced about 4,800 feet in the four hours since entering the mine just before 6 p.m. Another team entered the mine about 30 minutes later. He said the crew was very experienced, with some members having worked underground for 30 to 35 years. The miners were equipped with about one hour of breathable oxygen each. The company has not released the names of the miners. The teams test the air about every 500 feet, and have to disconnect (remove) the power to the phones they use to communicate with the suce before doing that. “We don’t want to be energizing anything if it’s in an atmosphere with burnable gases,” Kips said. The cause of the explosion was not immediately known. High levels of carbon monoxide were detected shortly after the explosion, which delayed rescue efforts, but those levels have since subsided（减退）, authorities said. 53. According to the passage, we can infer that ______. A. all the miners who were trapped underground were still alive B. communication with the trapped miners was cut off C. the two rescue teams entered the mine at the same time D. the rescue started as soon as the accident happened 54. If the first team advanced at an average speed, they could dig about ______ per hour. A. 1,000 feet          B. 2,400 feet           C. 1,200 feet                D. 4,800 feet 55. Where can the passage be seen? A. In a magazine.                                     B. In a newspaper. C. In a science book..                            D. On an advertisement. 56. Which of the following shows the position where the miners were trapped?