What type of systes are the following system?
Hot tea placed in a thermos flask.

Explanation

To determine the type of system represented by hot tea placed in a thermos flask, we will analyze the characteristics of different types of thermodynamic systems.

### Step-by-Step Solution:

1. **Understanding Thermodynamic Systems**:
- There are three main types of thermodynamic systems: open systems, closed systems, and isolated systems.
- **Open System**: Can exchange both energy and matter with the surroundings.
- **Closed System**: Can exchange energy but not matter with the surroundings.
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