…………….. Reactions never go to completion whereas ……………. Reactions proceed almost to completion.

Explanation

To solve the question, we need to fill in the blanks with the appropriate terms that describe the behavior of different types of chemical reactions.

### Step-by-Step Solution:

1. **Identify the types of reactions**: We need to differentiate between reversible and irreversible reactions.

2. **Understanding Reversible Reactions**:
- Reversible reactions are those that can proceed in both forward and backward directions.
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