But modifications needed for carrying astronauts could be costly and the launch alliance has also experienced delays and cost overruns.

但是为搭载宇航员而进行的修改花费高昂，联合发射联盟还深受工程延期和成本超支之扰。

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Worse yet, even if it were to be operational, military leaders say it would take more costly modifications to equip the MEADS system to handle our current and emerging military threats.

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It will also impose costly refinery modifications and require and necessitate increased importing of higher quality, non-California crude oil feedstock.

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