The present perfect tense spans two times, one is the past and the other is the present. Its action happened in the past, but it has an influence (or result) on the present, and this influence (or result) is often the speaker's interest, so there is often no adverbial of time behind it. The action expressed in the present perfect tense can be close to or far from the speaker's speaking time, such as:

The bus has arrived. Here comes the bus. (Result: The car is already at the door)

Someone broke the window. Someone broke the window. (Result: The window is still broken.)

He is ill. He just got sick. (Result: I don't look well now)

American English often uses the past simple tense instead of the present perfect tense, for example:

What happened? What happened? = What happened? )

Who took my dictionary? Who took my dictionary? Who took my dictionary? )

Table distance, for example:

He has traveled to many countries. He has been to many countries. (Result: He is well informed)

Have you ever seen the sea? Have you ever seen the sea? Result: If you have seen the sea, tell me what it is like.

She received a good education. She received a good education. (Result: Her education level is relatively high)

Sometimes you can use the present perfect tense to complete more than one action. For example:

They went to the moon and returned to the earth. They set foot on the moon and then returned to earth.

This river is a disaster for China. But we finally tamed it. This river is a disaster for China. But we finally tamed it.

Note that being there and being there have different meanings. Try to compare:

I have been to the library. I just got back from the library. Go back and use the present perfect tense of the be verb.

He went to the library. He went to the library. Go doesn't return. When you use the present perfect of Go, you can only use the third person.

It can also be used with infinitives. For example:

I went to see John. I went to see John.

This is one of the few times he has shed tears. This is his rare tear.

The present perfect tense is often used to indicate a continuous action or state, and it can also be used to indicate repeated actions in the past.

1) Infinite verb table persistence. Verbs expressing continuous action or state are mostly infinite verbs, such as live, study, teach, be, wait and so on. They are often used with words guided by since or for. For example:

I have lived here for more than thirty years. I have lived here for more than thirty years.

I have been here since last October. (because it is a preposition)

She has been teaching us since I came to this school. She has been teaching us since I came to this school. (as a conjunction)

In addition, since can also be used as an adverb.

Although the from clause is often used in the past simple tense, it can sometimes be used in the present perfect tense. In the present perfect tense, the self clause indicates the beginning of "period" or "self", but the verbs after it must be infinitely continuous. If the verb after since is infinite, but the tense is simple past tense, it means counting from the end of this action. For example:

I have often met him since I lived here.

I have often met him since I lived here.

I have learned a lot from him since I met him. I learned a lot from him.

Generally speaking, this present perfect will continue into the future. But it may not continue. For example:

Have you been waiting long? Have you been waiting long? If the speaker is the person the other person is waiting for, then the action will not continue. For is omitted before long, because long itself can be used as an adverb)

These shoes are worn out. They have been going on for a long time. These shoes are worn out. It's been worn for a long time. (what has been going on will not continue. For) was omitted long ago.

Non-infinite verbs are generally not continuous in the present perfect tense, but they can be continuous in the negative structure because the "negative state" itself can be continuous. For example:

I haven't bought anything for three months.

I haven't touched beer for a whole week. I haven't touched beer for a whole week.

2) You can also continue with a finite verb list. In contemporary English, some finite verbs break through the above rules, and in some cases, they can also be used with words guided by since or for to express "persistence". For example:

The two leaders have met for two hours. The two leaders met for two hours.

He has visited China for three days. He paid a three-day visit in China.

When did you become active? When did you start to be active?

However, it should be noted that the preposition for sometimes does not mean "experience" but "purpose". For example:

I've only been here a few minutes.

Charlie went to Canada for six months. Charlie will stay in Canada for six months.

3) List the repeated actions in the past. This present perfect tense is often used with adverbials of time, such as always, often, many times and every day. For example:

My father always goes to work by bike. My father always goes to work by bike.

It rained every day this week. It rained every day this week.

He tried six times and failed six times. He tried six times and failed six times.

It is also often used with a when clause containing another present perfect tense to express past experiences. For example:

I often met him when I was in London. I often saw him when I was in London.

Sometimes when I am alone, I think of that stupid thing. Sometimes when I am alone, I will think of that ridiculous thing.

The present perfect tense in the when clause is often replaced by the past simple tense. For example, here, someone was killed when shooting at a grizzly bear. )

Like the present simple tense, the present perfect tense can also indicate the future in the adverbial clause of time. For example:

We will go after breakfast. We left after breakfast.

How can you go before the rain stops? How can you leave before the rain stops?

I'll wait until he finishes writing the letter. I want to wait until he finishes writing the letter.

Noun clauses in the past tense. Like the present simple tense, the present perfect tense can also be used in noun clauses after the past tense, indicating that the speaker believes the truth of the content expressed in the clause. For example:

I heard that you were ill. I heard that you were ill.

The investigation proved that he had done his best. The results of the investigation show that he did his best.