 And now for the past perfect tense. This tense is used to talk about a past action and a related past action before that. In this case, we're relating two past actions to each other. We do so by using the auxiliary verb to have, but because we're talking about the past, we need to conjugate that auxiliary verb into the past, so we'll consistently use had no matter what our subject is for the sentence. The other critical part of the formation of this tense is the fact that the main verb needs to be put into the past participle form. Here, we've used a regular verb to finish and we've added ed. The results of sentences like su had finished, negative, su had not finished. We can contract had not into hadn't, and we can ask the question by saying, had su finished? As mentioned, the usage for the past perfect is to relate past actions that are in the past. So we always add the past perfect tense for the action that happened before the past action that we're talking about. So I want to say that we arrived in the past, but I also want to let you know that something happened even before we arrived. So I use the past perfect tense. Again, our auxiliary verb to have conjugated into the past, as well as our past participle form of the main verb. The resulting sentence could be something like, the concert had started by the time we arrived.