我们用过去完成进行时态来形容一个在过去开始的行动，这个行动持续到过去的另一个时间。
We use the past perfect continuous tense to show that an action started in the past and continued up until another time in the past.
英文摘要时态的运用也以简练为佳，常用一般现在时、一般过去时，少用现在完成时、过去完成时，进行时态和其他复合时态基本不用。
The use of tenses in English also is better to concise, commonly used present tense, the past tense, use less when completed, the past is finished now, tense and other composite tense basic need not.
英文摘要时态的运用也以简练为佳，常用一般现在时、一般过去时，少用现在完成时、过去完成时，进行时态和其他复合时态基本不用。
The use of tenses in English also is better to concise, commonly used present tense, the past tense, use less when completed, the past is finished now, tense and other composite tense basic need not.
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