The steel industry has changed radically over the last two decades, as large, integrated companies such as Bethlehem Steel once conducted operations from mining at one end of the process to shipping at the other have greatly downsized, or in some cases shut down altogether.
as large, integrated companies such as Bethlehem Steel
as large, integrated companies, such as Bethlehem Steel, that
with large, integrated companies, such as Bethlehem Steel, that
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有or沒有comma都是okay. 因為有comma, "that once conducted operations from mining at one end of the process to shipping at the other"是在modify "large, integrated companies" 沒有comma, "that once conducted operations from mining at one end of the process to shipping at the other"是在modify "Bethlehem Steel"