People are (1) ........ many sources of non-renewable energy these days. Oil and coal (2). ......... cheap to use and easy to find (3) .......... they cause pollution. Nuclear power is clean but can (4) ....... dangerous. Natural gas (5) ....... much pollution and (6) ......... lots of jobs but it’s difficult to get. There are many different kinds of non-renewable energy that people can choose to use. 1. a. to use b. using c. to using d. used 2. a. is b. are c. was d. were 3. a. and b. because of c. because d. but 4. a. am b. is c. are d. be 5. a. doesn’t cause b. don’t cause c. cause d. causes 6. a. makes b. creates c. goes d. travels