A. Circle the correct word to complete each sentence.
1. Natural gas is one of (the, an) most useful fuels.
2. Natural gas can be used to heat (a, an) home.
3. It is sent through (a, an) set of underground pipes.
4. (A, An) underground pipe goes to every house where natura
gas is used.
5. People in (an, the) house can stay warm all winter.