He stressed that any one person's fitness levels depend on a complex mix of factors, including genetics, exercise habits, body composition and overall health.
他强调道，任何一个人的健康水平取决于多方面因素的影响，包括遗传、锻炼习惯、身体成分及整体健康状况。
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These, together with reasonable guesses about the Earth's overallcomposition, have been used to put together the familiar model of an iron core, a rocky mantle and a thin crust.