11. They began studying at this school five years ago.
S + started / began + V-ing / to-V
= S + have/has PII + for (khoảng tgian)/since (mốc tgian)
12. I haven't watched this film before.
This is the first time + S + have/has + PII 
= S + have/has + not + PII + before
13. This is the first time I have attended such an enjoyable wedding party.
This is the first time + S + have/has + PII 
= S + have/has + not + PII + before
14. I last met him ten years ago.
S + last + Ved/V cột 2 (trong bảng động từ bất quy tắc) + khoảng tgian + ago
= S + have/has + not + PII + for (khoảng tgian)/since (mốc tgian)
15. They haven't visited me for five years.
S + last + Ved/V cột 2 (trong bảng động từ bất quy tắc) + khoảng tgian + ago
= S + have/has + not + PII + for (khoảng tgian)/since (mốc tgian)

11. They began studying at this school five years ago.
12. I haven't watched this film before.
13. This is the first time I have attended such an enjoyable wedding party.
14. I last met him ten years ago.
15. They haven't visited me for five years.

This is the first time+ MĐ Hiện tại hoàn thành

S+started/began+Ving+time ago

S+last+V(qkđ)+time ago= S+have/has not + V3/ed

This is the first time(Đây là lần đầu tiên) + MĐ Hiện tại hoàn thành= S+have/has not+ V3/ed+before