单项选择题 An alternative to plain old telephone service (POTS) would be:（）

单项选择题 Which of the following commands would be used to display hidden files?（）

单项选择题 A technician has a user that consistently picks up viruses and malware no matter what kind ofsoftware is installed to prevent infection. Which of the following should be a cost-effective logical step in preventing future infections?（）