6. 对国家规定或者经营者与消费者约定包修、包换、包退的商品,经营者应当负责修理,更换或者退货,保修期内( )修理仍不能正常使用的,经营者应当负责更换或者退货。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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