Those sources of energy which, once used, cannot be replenished soon or are lost forever are called ______sources of energy

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks for a term that describes energy sources that cannot be quickly replenished or are permanently lost once used.

2. **Identifying Key Characteristics:** These energy sources are characterized by their inability to regenerate in a short period. This means that once they are consumed, they either take a very long time to form again or may never be available again.

3. **Examples of Such Sources:** Common examples include fossil fuels like coal, oil, and natural gas. These are formed over millions of years and cannot be replaced quickly.

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