Answer the question according to instruction:
Knee joint : Name of lubricating fluid, name of two bones, type of joint.

Explanation

### Step-by-Step Solution:

1. **Identify the Lubricating Fluid**:
The lubricating fluid present in the knee joint is called **synovial fluid**. This fluid plays a crucial role in reducing friction between the bones during movement.

2. **Name the Two Bones**:
The knee joint is formed between two primary bones:
- **Femur**: This is the thigh bone, which is the upper bone of the knee joint.
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