One such investigation led to the arrest of the man accused of sending the extremely dangerous Melissa virus, a computer virus that destroyed files in computers around the world in the spring of 1999. The agents received help from online service technicians, software experts, and a computer-science student. All helped to trace the complex pathways of the virus back to the telephone line and computer of the man who released it.  
In another case, agents worked for two years to catch a cybercriminal who was, among other offenses, stealing credit card numbers. Agents found him by tracing a path from a computer he broke into to the mobile telephone he had used, which led to his address—and arrest.  
The gobernment agents are also working to block cybercriminals who could cut off power and confuse telephone companies.”Think of the consequences if  the power went out for a week—not in just one town or city but down the whole Eat Coast,” says Michael Vatis, an FBI agent. From TVs to hospital equipment, all would fail.  
Makaveli and TooShort were arrested for the charges of breaking into computers. They were given probation, required to perform community service, and prevented from having home computers with modems. Punishment for adults can be more severe and usually includes some jail time.  
Most people use their computers legally. For the few who don’t , however, cyberpolice and better security systems will make it harder for cybercriminals to get away with their crimes.  
36.What should be known to catch cybercriminals?  
A.   Credit card numbers.  
B.   Suspects’fingerprints.  
C.   The technology used to commit the crimes.  
D.   Numbers, symbols and letters.  
37. How dangerous was Melissa virus back in 1997?  
A.   It destroyed computer files worldwide   
B.    Many agents took up the case  
C.    Technicians, experts, and a student were investigated  
D.    Telephone lines and computes were destroyed.  
38. How serious could a computer crime become?  
A.   Many telephone companies would go bankrupt.  
B.   A city would be thrown into darkness.  
C.   Power would be out down the east coast for a week.  
D.   There would be no more television programs to watch.  
39. What can we infer about the process of catching computer criminals from the passage?  
A.   It could be dangerous.  
B.   It is rather complicated to identify the cybercriminals.  
C.   It would cause a huge loss.  
D.   It has been a severe punishment.  
40. The last sentence of the passage may serve as a_____? 

A. warning             B. complaint  
C.suggestion            D. command  
Passage Three  
Earth’s most rich resource—water—has become one of the most precious resources in the United States as rivers, lakes, and freshwater reservoirs are increasingly exploited for human use . Consequently, using precision farming techniques to refine” irrigation scheduling ” is a research area of particular interest to Susan Moran, a researcher with the U.S. Department of Agriculture. She explains that in the southwest, irrigation is both difficult and expensive .There, she says, farmers have a tendency to  over-irrigate, spending both more time and money than is necessary.  
“I’m trying to provide new information that could be used by farmers to schedule irrigations to improve their profitability and use less water, ” Moran says. “Farmes often look at weather changes and then schedule irrigation based on that information .But if they had better information , they could use scientific models to compute more precisely how much water their crop is using.”  
Rather than guessing their crop’s potential need for water based upon weather changes, farmers can use remote sensors to measure how much water their crop is actually using. This would give them a more accurate measure of how much more water it needs.