شرکت در آزمون آنلاین زبان انگلیسی 1 - زبان انگلیسی 1 | آزمون شماره 9175

So far we haven’t been able to find much about this metal, but we are still ......... on it.

These two cars are ………, but the red one is much more expensive than the blue one.

Titan is slightly bigger than the planet Mercury, and is called a moon only because it … the giant planet Saturn rather than the Sun.