Present Perfect Simple

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..... I call this tense  the lost past. Because It refers to a past action that has no definite time. That is :  we don't know when it happened exactly

1)Forms: 

A) Affirmative form

Subject + has ( she/he/it) or have ( I , You,  they , we ) + pas participle of the verb

Example:  

_ I have  bought a new car .
_ she has eaten alot of meat
_ they have drunk alot

B)Negative form:

Subject + hasn't/ has not ( she , he , it ) or haven't/ have not ( I,  You,  they , we)+ past participale

Example:

_She hasn't called her husband since last week.
-They have not gone to America.
-It has not worked.

^{C)Interrogative form}

Has/ have + subject  + past participale of the verb

Example:

_Have you ever tasted sushi ?
_ has she called her boss ?
_ have they invited you?

2)Indicators:

Yet / so far / ever / never / since / already/ just / lately / recently  / for + ( number of ( weeks, years,  hours , days , seconds....))