Windmills or wind turbines harness- to drive generators which produce electricity.

Explanation

To solve the question "Windmills or wind turbines harness _____ to drive generators which produce electricity," we need to identify what these devices utilize to generate power.

### Step-by-Step Solution:

1. **Understanding Windmills and Wind Turbines**:
- Windmills and wind turbines are devices designed to convert wind energy into mechanical energy.

2. **Identifying the Source of Energy**:
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