About the difference between the present perfect tense and the past perfect tense

Present Perfect Tense: (1) Emphasizing that the action is that happened in the past (2) Emphasizing the impact or result on the present (3) The action that took place in an uncertain time in the past, but the result has an impact on the present. The main embodiment is the past - the present.

Past Perfect Tense: Indicates an action that was completed at a certain moment in the past or before the action, and it can also be said that the past time is about the past action. That is, "the past of the past".

It can be represented by a prepositional phrase such as by, before, or a temporal adverbial clause, or by an action that indicates the past, and perhaps by context. Mainly embodies the past - the past.

This I will, the present perfect tense and the past perfect tense, is the most headache for me, I consulted my teachers and classmates, I figured it out, and now I will share it with you.

Let's take a look at these two sentences:

tom lost his key.

tom has lost his key.

After reading it, you will find that they can all be translated as "he lost his key", that is, they all refer to what happened in the past "lost the key". But it is clear that they use different tenses: the first sentence is in the past tense; The second sentence is in the present perfect tense.

Since they use different tenses, then there must be a difference between them! For the sake of understanding, let's reinterpret these two sentences and see what is the meaning behind them.

The first sentence is used:Past tense, it actually emphasizes that "the loss of the key happened in the past", if we interpret it further, we have to ask if he has found it now? The answer is no! The past tense only mentions the past, and in its concept, it has nothing to do with the present, and now he may or may not have found the key, and the sentence does not say it at all.

The second sentence is:Present perfect tense"Present Perfect Tense" From the concept, we know that he emphasizes the present and mentions the past, which can be understood to mean that Tom lost his key in the past, and it emphasizes the "present", which has not yet been found

You should be able to understand by now that these two sentences have something in common: they can both indicate that Tom lost the key, because both tenses refer to things that he did in the past, but to express them in the past tense is to explain the things of the past, and now I don't know what happened to him; And in the present perfect tense, the emphasis is on the impact of the loss on the present, they lost her key, and he has not found it yet.

If you can initially understand these two tenses, you will get started with the study of tenses! That's all for me.

The present perfect tense is the present past.

The past perfect tense is the past of the past.

When you arrived yesterday, I had already cleaned up. Past Perfect Tense.

You're only here now, and I've cleaned it all. Present perfect tense