공유 오디오

Hello, class. Today I’d like to tell you about two energy sources. They are non-renewable sources and renewable sources. Non-renewable sources are coal, oil and natural gas. We can use these sources to produce energy. They are cheap and easy to use. People use them a lot. But they are very limited …

Hello, class. Today I’d like to tell you about two energy sources. They are non-renewable sources and renewable sources. Non-renewable sources are coal, oil and natural gas. We can use these sources to produce energy. They are cheap and easy to use. People use them a lot. But they are very limited and will run out soon.