1. We can never expect ___ bluer sky unless we create ___ less polluted world.
A. a; a B. a; the C. the; a D. the; the
2. The biggest whale is ___ blue whale, which grows to be about 29 meters long—the height of ___ 9-story building.
A. the; the B. a; a C. a; the D. the; a
3. At a rough estimate（估计）, Nigeria is ____ Great Britain.
A. three times the size as B. the size three times of
C. three times the size of D. three times as the size of
