Some researchers believe that there is no doubt ____ a cure for AIDS will be found.

May Day is coming. I’ll ________ up my room. I don’t want to live in a dirty place.

What do you usually have for breakfast?—A piece of bread and ________ egg.

Because of Project Hope,_______children have better lives.

Is the Youth Center open to the public yet?—Yes. It ______ for almost one and a half years.