scientists
                    - Scientists are working hard to make _______ possible for people to live on Mars in the future.
 - Many scientists say that it’s important for us to have ______ food in our diet.
 - Scientists are working hard to make _______ possible for people to live on Mars in the future.
 - Many scientists say that it’s important for us to have ______ food in our diet.
 - The scientists ________ on the new medicine for two years. They will succeed in no time.
 - It’s said that scientists have ________ a way to deal with the serious disease
 - Most scientists seem to agree that ________ certain limit should be set on ______sale of cars to ease air pollution.
 - _____ scientists could make clones of human beings?[ ]