过去完成时

the perfect tense───完成时

past perfects───（动词的）过去完成时

perfect tense───完成时态

past perfect───（动词的）过去完成时

perfect sense───完美的感觉

perfect tenses───完成时态

past experience───过去的经验

Learn to express something with Past Perfect Tense.───学习使用过去完成时态。

As you correctly stated, the past perfect tense is used in a sentence that describes two past events that happened at different times, as in the following.───依据你正确的陈述，过去完成式是使用在一个句子里陈述两件过去发生在不同的时间的事情，看下面的例句。

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.───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。

Learn to express something with Past Perfect Tense.───学会描述过去所发生的事情.

When research process narration mentioned before what described by past tense , we had better use the past perfect tense.