Friction always…….

Explanation

To answer the question "Friction always...", we need to fill in the blank with an appropriate phrase that describes the fundamental nature of friction.

### Step-by-Step Solution:

1. **Understanding Friction**: Friction is a force that arises when two surfaces are in contact with each other. It acts to resist the sliding motion between the surfaces.

2. **Identifying the Role of Friction**: The primary role of friction is to oppose the motion of one surface relative to another. This means that if one object is trying to slide over another, friction will act in the opposite direction to that motion.

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