In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Q: Question: Why did people stop adding lead to gasoline? Answer: environmental pollution

A: People stopped adding lead to gasoline because of environmental pollution.
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Q: Question: The cubic crystal system is composed of how many different types of unit cells? Answer: three

A: The cubic crystal system is composed of three many different types of unit cells.
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Q: Question: Spindle fibers form between the centrioles during prophase i of what process? Answer: meiosis

A:
Spindle fibers form between the centrioles during prophase i of meiosis process.
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