Working from home is more and more popular as a means of escaping the ninetofive office life. Why do you work under the eye of your boss when you can work in front of the TV in your slippers?Armed with all the necessary things--telephone, computer, email and fax,many workers believe they can work as effectively as their colleagues in the office. Being able to work wherever you like:from a busy city to a village, and not having to stand the daily things, make working from home an attractive choice. If you wish,you can even work on a river boat. So what will become of the office tomorrow?It is possible that many could go into computer space creating a new wave of virtual  offices. To minimize office in innercity areas, companies will have a work force made up of a network of home workers linked by an advanced communication and information system. A central processing computer would be controlled by the manager who sends out work schedules and oversees  the activity of each employee. A video screen would be created,as the need for email or telephone becomes greater. Seeing the mood and expressions of work colleagues, managers would have the ability to view several employees at once on their screen. Employees would be encouraged to feed any information that may be useful to fellow workers into the computer to make the company work more effectively. As the company's lifeblood, the computer would contain a record of all conversations and communication for future reference and hold secret information such as accounts in password  protected areas. According to the passage, which of the following things is NOT necessary for a virtual office?
A manager. An office building. A telephone. A central processing computer.