`1`

`(-)` I haven't finished my hw. 

`(?)` Have you finished your hw?

`2` 

`(+)` My uncle has been to Singapore before.

`(?)` Has your uncle been to Singapore before? 

`3` 

`(+)` They have found their keys . 

`(-)` They haven't found their keys .

`4` 

`(-)` Jim hasn't played video games with his brother.

`(?)` Has Jim played video games with his brother?

`5` 

`(+)` My grand mother has visited me since November.

`(?)` Has my grand mother visited me since November?

`=>` Công thức hiện tại hoàn thành

`(+)` S + have / has + Vpp + .....

`(-)` S + haven't / hasn't + Vpp + .....

`(?)` Have / has + S + Vpp + ..... ?

I, you, we, they + have / haven't

he, she, it + has / hasn't