Complete the following sentence : Resonance is a special case of ........ vibrations, when frequency of the driving force is ........... natural frequency of the driven body.

Explanation

**Step-by-Step Solution:**

1. **Understanding Resonance**: Start by defining what resonance is. Resonance occurs when an object vibrates at its natural frequency due to an external force.

2. **Identifying the Type of Vibration**: Recognize that resonance is a specific type of vibration. In this case, it is a special case of forced vibrations. Forced vibrations occur when an external force causes an object to vibrate.

3. **Frequency Comparison**: The next part of the sentence requires us to compare the frequency of the driving force with the natural frequency of the driven body.

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