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来源:雅诚德英语网
Up until now there've only been three known strains of HIV, the virus that causes AIDS.
目前为止,仅有三种导致艾滋病的HIV病毒毒株。
Up until now there've only been three known strains of HIV, the virus that causes AIDS.
目前为止,仅有三种导致艾滋病的HIV病毒毒株。