______ can tell you where the user is on the earth

单项选择题

The Internet, mobile phones and iPads are part of our lives now. Technology is greatly affecting all ways of our lives, from the ways we work to the ways we play. And it even causes a number of social problems such as cloning humans. We had lots of technology and it has changed our lives a lot. There is no doubt that humans will continue to use more and more technology. Here are some examples of modern technology that will change our ideas and will affect our lives greatly.
Global Positioning System:
It"s a system that uses radio signals from satellites to show exact information. It tells you where the user is on the earth in all weather conditions. It"s made up of three parts: satellites, control equipments on land and receivers.
Space Technology:
Russian and American scientists have worked together for the International Space Station for a long time. They hope the ISS will provide a long-lasting lab. Such a lab will bring humans limitless advantages. It"s even hoped that one day spare technology will take humans to their new houses in space.
Underwater Robot:
Hercules is a kind of under water robot with some high technology equipments. It will be used to search for ancient ships which were destroyed into deep sea during their journey long ago.
The world is changing so quickly that it is hard for us to catch up with all the new inventions because they seem to come out every month. It is important for us to learn about new technology and the role that it plays in our lives. So we should be willing to accept modern technology, or we will fail behind the times.

______ can tell you where the user is on the earth.

A．Satellites
B．Receivers
C．GPS
D．Underwater Robot