She kept a penny for luck.
Meaning: She held on to a penny because she believed it would bring her good fortune.
Choice of Words: Kept means to have something in one's possession or control. A is an indefinite article that refers to a single, unspecified item. Penny is a coin worth one cent. For is a preposition that indicates a purpose or reason. Luck is a positive outcome that is believed to be caused by chance.
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