1. They last went fishing 2 years ago.

-> They haven't

2. It is 3 months since she saw them.

-> She

3. The last time he visited his hometown was when he gradua from university.

-> He

4. We started doing business in 2015

-> We

ĐÁP ÁN:

1. They last went fishing 2 years ago.

→ They haven't gone fishing 2 years.

→ Dịch: lần vuối họ đi câu cá là cách đây 2 năm.

2. It is 3 months since she saw them.

→ She seen them since 3 months.

→ Dịch: Đã 3 tháng kể từ khi cô gặp họ.

3. The last time he visited his hometown was when he gradua from university.

→ He has visited his hometown since he gradua from university.

→ Dịch: Anh ấy về thăm quê hương kể từ khi anh ấy đỗ đại học.

4. We started doing business in 2015.

→ We have done businiess since 2015.

→ Dịch: Chúng tôi đã kinh doang từ năm 2015.

GIẢI THÍCH:

Công thức chuyển đổi từ Quá Khứ Đơn ⇔ Hiện Tại Hoàn Thành

1. S + last (lần cuối) + V-ed, thời gian quá khứ.

→ S + haven't/ hasn't + V.p2 + since/ for.

2. It is + lượng thời gian + since + S + (last) + V-ed (Bao lâu rồi . kể từ khi . . . lần cuối . . .)

→ S + haven't/ hasn't + V.p2 + since/ for.

3. The last time + S + V-ed was + thời gian quá khứ (lần cuối . . . làm là . . .)

→ S + haven't/ hasn't + V.p2 + since/ for.

4. S + start/ began + V-ing + thời gian Quá Khứ

→ S + has/ have + V.p2 + since/ for.

`1.` They haven't gone fishing for 2 years.

`2.` She last saw them 3 months ago.

`3.` He hasn't visited his hometown since he graduated from university. 

`->` S + have/has + (not) + P2 + since + S + Ved

`4.` We have been doing business since 2015.

`--------------------`

`+` It's + thời gian + since + S + (last) + Ved

`=` S + last + Ved + thời gian + ago

`=` The las time + S + Ved + was + thời gian + ago

`=` S + hasn't/haven't + P2 + since/for....

`+` S + started/began + Ving/to V

`=` S + have/has + been Ving + since/for...