问题
单项选择题
The successful spread of a virus depends on how long it can (74) unnoticed, before its presence is made known by the activation of side-effects. For example, many viruses (75) their code to avoid recognition.
A．move
B．replicate
C．backup
D．die out
答案
参考答案：B
解析： 译文：计算机病毒能否成功地传播依赖于它是否能在不被发觉的时候不断复制。