Grammar: Present perfect simple (Affirmative & Negative).

Form of the Present Perfect

We form the Present Perfect with have and the past participle 
(regular verbs: infinitive + -ed; irregular verbs: 3rd column of the table of the irregular verbs)

have/has + past participle

has: 3rd person singular (he, she, it)

have: all other forms

past participle:
- regular verbs: infinitive + -ed
- irregular verbs: 3rd column of the table of the irregular verbs

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Affirmative sentences

regular verbs	irregular verbs
I/we/you/they have opened the window.	I/we/you/they have gone to the supermarket.
He/she/it has opened the window.	He/she/it has gone to the supermarket.

NOTE: We use has in the 3rd person singular (he, she, it).

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Negative sentences

regular verbs	irregular verbs
I/we/you/they have not opened the window.	I/we/you/they have not gone to the supermarket.
He/she/it has not opened the window.	He/she/it has not gone to the supermarket.

NOTE: We use has in the 3rd person singular (he, she, it).

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Questions

regular verbs	irregular verbs
Have I/we/you/they opened the window?	Have I/we/you/they gone to the supermarket?
Has he/she/it opened the window?	Has he/she/it gone to the supermarket?

NOTE: We use has in the 3rd person singular (he, she, it).