THE FIRST FISH (APPEAR) __________ ON THE EARTH ABOUT 500 MILLION Y...

4. - REVISION EXERCISES FOR GRADUATION EXAM
REVISION EXERCISES FOR GRADUATION EXAM
4. The first fish (appear) __________ on the earth about 500 million years ago. Up to now, over 20,000 kinds of fish (name) __________ and (describe) __________ by the scientists. New species (discover) __________ every year, so the total increases continually.