Correct the following statements by changing the underlined part of the sentence (Do not change the whole sentence)
Cells which do not have indefinite life and become dead over a period of time are called `ul("secondary cells.")`

Explanation

To correct the statement, we need to replace the underlined part "secondary cells" with "primary cells."

**Corrected Statement:**
Cells which do not have indefinite life and become dead over a period of time are called **primary cells.**

### Step-by-Step Solution:

1. **Identify the Key Terms**: The original statement refers to cells that do not have an indefinite life and eventually become non-functional. The terms "secondary cells" and "primary cells" are crucial to understanding the classification of electrochemical cells.
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