It is believed that part of animals can’t stay alive in water at 1,500 meters below ____ sea level.
When I went to the lake, my father was__________ fishing.
He is always full of __________ as though he has neverknown tiredness.
At present we have no __________ of life on otherplanets.
This book __________ ten units,__________ three main revision.
—I think arts are more interesting than science ones. —__________. I prefer science subjects.