Final answer:
The phrase 'Il est quatre heure et de quart (4h15)' is not grammatically correct in French.
Step-by-step explanation:
The given phrase, 'Il est quatre heure et de quart (4h15)', is not grammatically correct.
The correct way to express '4:15' in French is 'Il est quatre heures et quart'. The word 'et' is used to connect the hour ('quatre heures') with 'quart' to indicate 'a quarter past'. The phrase 'et de quart' is incorrect.
Therefore, the correct grammatical expression for '4:15' in French is 'Il est quatre heures et quart'.
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