When we talk about experience and results, we use the present perfect form. 

This form uses have followed by the participle.分词

For regular verbs, this participle is identical to the past tense form.

For irregular verbs, this participle is often different.

When we use the perfect form, the primary focus is on the subject of the sentences, not the verb.

It emphasizes condition, experience or results, rather than actions or events.

In these two examples we see the contrast.

The top sentence gives the condition or state of the subject, and the bottom sentence expresses an event.

The top sentence decribes the condition of the subject of the sentence:"she", rather than an event.

The fact that she has left the hotel, is now a part of her experience or state of being.

The bottom sentence expresses the action or event, she left, which is something she did.

In general, the past tense form expresses events or acts, and the perfect form expresses experience or conditions.

When we use the perfect form of the verb, we focus on the state of the subject, not an action or event.

Note that the past tense form expresses events at specific points or periods of time, such as last year or the past five years. 特殊的，特定的；明确的；

These events are distanced from the speaker's point of view.

The perfect form expresses the state of something from the speaker's point of view, not distanced in time.

These two sentences are incorrect and confusing because they give two different points of view.

Here are some sentences that use the perfect form.

Some are simple, such as the first one, and some are complex, like the last one.

The last one is complex because it combines many verb forms, including the passive.

(He may have been injured in the explosion.)

(He may have taken his computer with him, but I'm not sure if he did or not.)