Most air pollution is caused by the burning of _________ like coal, gas and oil. 

Every one of us is free to have our own religious _______.

An increasing number of people enjoy sun-bathing, but experts warn that too much ________of the body to strong sunlight is harmful．

Our school has an absolute _______ over others, for we have the most hardworking teachers and students.

 —Excuse me, may I ask you some questions? ---Sorry, I’m too busy and haven’t even a minute to________.