PRESENT PERFECT

The Perfect Present helps us to talk about past actions that have some connection with the present. For example: 

• He has found a cat
• We have known each other for a long time

HOW TO USE IT

When we talk about an action that took place in the past, but we did not specify when it happened, we use the present perfect. We can say that when we do not specify the time, we are placing the action in the course of our lives, that is, at some point from birth until now.

Here we have the relationship with the present of this use of the present perfect.

• He has been to Cincinnati – Where?
• They have studied English Philology – At some point in their lives

There are actions of the past whose relationship with the present is very clear, an example are those that began in the past and still happening in the present.

• She have worked here since 1998 -  and still work here
• I have lived here for 5 years - and still live here

 Another example is when what happened in the past has a direct effect on our current situation.

• She have lost her keys - How can she goes home now?
• I have studied at lot - I will pass the exam today

HOW IS FORMED

To form the perfect present, we must use the correct form of this auxiliary verb "to have", "have" or "has", followed by the past participle of the verb desired.

Let's see how it works:

1. AFFIRMATIVE FORM

SUBJECT+ HAVE/HAS+ VERB (PARTICIPLE) + (COMPLEMENT)

SUBJECT+HAVE/HAS	PARTICIPLE	COMPL.
I have/I’ve	eaten	bananas
You have/You’ve
He has/He’s
She has/She’s
It has/It’s
We have/We’ve
You have/You’ve
They have/They’ve

As happened with the simple past, how to form the participle will depend on whether we use a regular or irregular verb.

The regular participles are exactly like the simple past, adding "-ed" form. If the verb is irregular, we will have to resort to the list of irregular verbs, where the participle of each verb is specified.

2. NEGATIVE FORM

As in any negative form, the present perfect is added 'not'. You can also contract by adding 'not' to the corresponding auxiliar form.

• She hasn’t bought the book
• You haven’t come to the party

SUBJECT+ HAVE/HAS + NOT + VERB (PARTICIPLE) + (COMPLEMENT)
 

SUBJ.+HAVEN'T/HASN'T	PARTICIPLE	COMPL.
I have not/I haven't	drunk	tea
You have not/You haven't
He has not/He hasn't
She has not/She hasn't
It has not/It hasn't
We have not/We haven't
You have not/You haven't
They have not/They haven't

3. INTERROGATIVE FORM

To form the question, we apply a rule that already dominate: we must reverse the order of subject and auxiliary.

(WH-WORD) + HAVE/HAS + SUBJECT + PARTICIPLE + (COMPLEMENT) ?
 

WH-WORD	HAVE/HAS	SUBJECT	VERB (PARTICIPLE)
Why	have	I	left?
		you
	has	he/she/it
	have	we
		you
		they

Note that to be polite to answer questions starting with the auxiliary (questions that can be answered simply with 'yes' or 'no'), we have to use short answers.

• Have you eaten yet? - Yes, I have / No, I haven’t