阅读理解。 The men dressed as police officers stole about $200 million worth of art from the Isabella Stewart Gardner Museum early this morning. The two burglars(窃贼)knocked on a side door of the museum at about 1:15 am. They told the two security guards who were on duty that there was a disturbance in the area. The guards then made the very serious mistake of allowing the two men to go into the building. After they went in, the two burglars tied the guards up with tape. The two men spent about two hours in the museum. During that time, they stole 11 paintings and an ancient Chinese vase. The stolen works included three paintings by Rembrandt. A maintenance(保卫)worker discovered the two guards at about 7 am and called police. One of the greatest losses was Rembrandt's works, ' The Storm on the Sea of Galilee.' It was a very popular attraction at the museum and was one of the most valuable works stolen. Museum officials said that the value of the stolen art is at least 200 million dollars, and may in fact be much more. The true value of the paintings is unknown, because they have not been on the market for nearly a century. According to law enforcement officials, this is considered to be the biggest theft ever in the United States. Officials are waiting to see whether the burglars will demand a ransom for the paintings or try to sell them to a private collector. Museum officials and police are not sure why the burglars chose certain works and not others. There are other paintings in the museum that are even more valuable than the ones that were stolen. Special investigators are looking into the theft and the museum's security system. They believe that this is a 'professional job', because the people involved were well prepared and knew what they wanted. Investigators have already questioned the museum's guards extensively. They would not give the names or ages of the guards, but one investigator said the Gardner hires and trains its own security staff. So far, the guards have not been identified as suspects in the case. An investigator said that anybody having any information about the robbery should contact the Boston Police Department immediately. 1. We can infer from the passage that . A．the security guards didn't identify the false policemen B．the police had accurate ideas of the robbery after investigating C．the burglars didn't dare to sell the stolen things on the market D．the security guards helped the thieves secrectly 2. According to the passage, ' The Storm on the Sea of Gal ilee' was the following except that . A．it was Rembrandt's works B．it was the most valuable work at the museum C．it was very attractive to visitors D．it was one of the greatest losses 3. Which of the following best explains 'demand a ransom for the paintings'? A．Hide the paintings in a secret place. B．Send the paintings to some foreign countries. C．Ask for money to give the paintings back. D．Change them into more valuable things. 4. The investigators believe that this is a 'professional job' because the burglars . A．didn't steal the most valuable works B．made careful plans about the theft C．tied the guards up with tape D．were dressed as police officers 5. According to the passage, ______ A．the art works stolen from the Isabella Stewart Gardner Museum are valueless. B．it is illegal for the Isabella Stewart Gardner Museum to train its own guards. C．the security guards on duty that day are suspected. D．the works stolen haven't been traded for about 100 years.