A system is said to be in ...... equilibrium when the system and the surroundings are at the same temperature.

Explanation

To answer the question, we need to identify the type of equilibrium described in the statement.

### Step-by-Step Solution:

1. **Understanding the Concept of Equilibrium**:
- Equilibrium in thermodynamics refers to a state where there are no net changes occurring in a system. This can involve various types of equilibrium, such as thermal, mechanical, and chemical equilibrium.

2. **Identifying the Type of Equilibrium**:
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