1. We haven't taken part in an international summer camp since I was a medical student.

→ S + (last) + V2/ed + O + when + S + V2/ed

                                             time + ago

= S + have/has + not + V3/ed + O + since + S + V2/ed

                                                             for + time

2. Mary pains more creatively than her sister.

→ so sánh hơn với trạng từ dài: S1 + V + more + Adv + than + S2

3. Despite their careful preparation, they had a lot of difficulties in making the film.

→ Although + S + V, S +V: Mặc dù ... nhưng ...

= Despite/ In spite of + N/V_ing, S + V

`1.` We haven't taken part in an international summer camp since I was a medical student

`=>` thì hiện tại hoàn thành

`=>` Dấu hiệu: since

`=>` S + have/has + (not) + Vpp + O

`2.` Mary pains more creatively than her sister

`=>` So sánh hơn:

`->` Tính từ dài vần: S + V + more + adv + than + S

`3.` Despite their careful preparation, they had a lot of difficulties in making the film

`=>` Despite + N / Ving, S + V + ...