题目

In today’s world, we rely on computers as never before. They are used for everything from ordering a pizza to running hospitals and military defense systems. Banking and credit card information is stored and accessed by computers. So what happens when a computer gets infected with a virus? One effect is that people’s access to their e-mail accounts is cut off. A more serious possible consequence is that billions of dollars could be lost. A virus is a computer program that copies itself onto other programs and infects them. Similar to an easily spread disease, a computer virus goes from com（2011?福州）青蛙在繁殖时期特有的行为是（　　）A．抱对B．游泳C．迁徙D．跳跃