Give one function : Pleural fluid.

Explanation

### Step-by-Step Solution:

1. **Understanding Pleural Fluid**: Pleural fluid is a liquid found between the two layers of the pleura, which is the membrane surrounding the lungs.

2. **Identifying the Layers of the Pleura**: The pleura consists of two layers:
- **Parietal Pleura**: The outer layer that is attached to the chest wall.
- **Visceral Pleura**: The inner layer that is attached to the lungs.

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