Helpppppppp cần gấp ạ

`26` Haven't you visited to our country before?

`27` We haven't contacted for 3 months.

`28` I haven't written to her for a long time.

`29` How long have you waited for the bus?

`30` I have stayed in this hotel once before.

`31`

`-` The last time he sent me postcards was when he was in Paris.

`-` He hasn't sent me postcards since he was in Paris.

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`@` Biến đổi Hiện tại hoàn thành `<=>` Quá khứ đơn

`1.` S + haven’t/hasn’t + Ved/Vpp + since/for + time

`=` S + last + Ved/V2 + time

`=` The last time + S + Ved/V2 + was + time

`2.` S + have/has + Ved/Vpp + since/for + time

`=` S + started/began + to V/V-ing + time

`3.` When + did + S + V-inf?

`=` How long + have/has + S + Ved/Vpp?

`4.` It/This is the first time + S + have/has + (ever) + Ved/Vpp

`=` S + haven’t/hasn’t + Ved/Vpp + before

`=` S + have/has + never + Ved/Vpp + before

`5.` S + haven’t/hasn’t + Ved/Vpp + since/for + time

`=` It is/It has been + time + since + S + last + Ved/V2