A、They can be built to be very light. B、They are inexpensive to operate. C、They can be directed by remote control. D、They easily

The very success of satellite communications systems has raised widespread concern about their future. Some countries are already using satellites for domestic communications in place of conventional telephone lines on land. Although this technique is extremely useful for linking widely scattered villages in remote or mountainous regions, in heavily built-up areas where extensive telephone and telegraph systems already exist, domestic satellites are seen by the land-line networks as unfair competition. Despite such opposition, domestic satellites are gaining support from many businesses and public interest groups in the United States and seem likely to be more widely utilized in the future.