HMDs were first demonstrated in 1980.

Given the following Classical-type table shows the number of days of labor input required to obtain one unit of output of each of the three commodities in each of the two countries: Suppose that the wage rate in the United Kingdom is £30 per day, the wage rate in the United States is £40 per day. In this situation, the United Kingdom will ___________.

Except for major cities, APA style uses the two-letter postal abbreviation to identify the state in which the publisher is located.

It is much easier to create the haptic interface than the visual one.

VR can be made better uses on networks in the future.

It is necessary that those computer-controlled motors to generate force feedback be made as small as possible because they have to be put on the user's body.

Sometimes the images on two LCDs and sounds through two earphones are slightly different so that the virtual world appears more real.

VR participants can not easily tell a simulation from physical reality.

Virtual-reality devices not only transmit sounds to the user, but also record and send his speech to the program.

One of the shortcomings of a virtual-reality system is that it enables only one person at a time to use it.

We can infer that current virtual reality devices ______.