Why do you keep this completely ____ umbrella, which is broken?

6. As there is less and less coal and oil, scientists are exploring new ways of making use of   energy, such as sunlight, wind and water for power and fuel.

After the explosion，the roads are full of ________people leaving the city. 

——John always thinks of others instead of himself.—— So he does. It is _______ of him to want to help others.

Evidence has been found through years of study that children’s early sleeping problems are _______ to continue when they grow up.