___ scientists are working on trying to bring extinct species back to life.

___ scientists agree that we need cleaner energy.

I tried three methods, but ___  of them worked.

___ scientists received an award.

The project has not gone well, and there is now ___  chance that it will succeed.

They produced two cloned animals, but ___ one lived for very long.

___ new discovery takes us one step closer to a cure for the disease.

Solar energy doesn’t cause any pollution, and wind power doesn’t ___ .