（ ）are utilized to relay Enhanced Group Calls A: COSPAS satellites. B: HF SITOR shore stations C: NAVTEX shore stations D: Inmarsat satellites.

The 24 satellites in the Global Positioning System ( GPS ) are synchronous satellites, and they appear to be stationary to an observer on the earth.

The previously __________ objects have now been identified as being satellites.

These satellites constantly transmit an identifying .

In the GPS system, the two known points are provided by one GPS satellites.

One or two man-made satellites _______ in this country every year.

Geostationary satellites are the man-made satellites which . A: are always fixed in the regular position B: sometimes move with the earth C: are synchronizing with the movement of the earth D: can not fly off from the ground

Why do we use the weather satellites to take pictures of the atmosphere? Because __________.

The photos of Mars taken by satellites are (clear) ______ man those taken from Earth.

It is possible to use satellites to predict earthquakes because satellites ________. A: take pictures of the Earth B: catch radio waves sent from the Earth’s surface C: are sensitive to Earth’s movements D: see almost the entire Earth