In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

Q: A mercury-arc valve or mercury-vapor rectifier or ( UK ) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-current alternating current ( AC ) into direct current ( DC ) .

A: A Mercury-arc rectifier is a type of rectifier used for converting alternating current ( AC ) to direct current ( DC ) .
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Q: In economics , utility is the satisfaction or benefit derived by consuming a product ; thus the marginal utility of a goods or service is the change in the utility from an increase in the consumption of that good or service .

A: Marginal utility is a concept from economics that describes the change in utility from consuming more or less of a good or service .
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Q: The Penguin ( Oswald Chesterfield Cobblepot ) is a fictional supervillain appearing in comic books published by DC Comics , commonly as an adversary of the superhero Batman .

A:
The Penguin ( Oswald Cobblepot ) is an enemy of Batman in DC Comics .
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