Recycling is one way to protect the environment; reusing is ________.
The text is too difficult. The explanation of our teacher will help make it easy ________.
It is said that sixty percent of all energy ________ in the world today is being lost as waste heat.
________ clearly ________ nothing to do, the soldiers left the village the next day.
—I regret ________ you that your application has not been successful.—Not successful? I performed pretty well in my interview!
As is known to all, one of the many benefits of ________ adventure travel is teaching children how to cope with ________ unexpected.