`48,` Mr. Thi hasn't taught in Le Quy Don since August, 2021.

- Cấu trúc:

S + have/has not + V3/ed + O + since + mốc thời gian

= The last time + S + V2/ed + O + was + since + mốc thời gian

- Dịch: Ông Thi đã ko dạy ở Lê Qúy Đôn từ thắng 8, 2021

`50,` Although the weather was bad, we went out for a picnic.

- Despite/In spite of + N/N phrase/Ving = Although/Though/Even though + S + V: mặc dù ...

`-` Dịch: Mặc dù thời tiết xấu, chúng tôi đã đi dã ngoại.

`48.` Mr.Thi hasn't taught in Le Quy Don Junior High school since August 2021. 

`-` Cấu trúc: The last time + S + V-ed + O + was + time + ago/ in/when + time

`=>` S + haven't/hasn't + VpII + ... + since + time/for + time

`49.` We went out for a picnic although the weather was bad.

`-` Cấu trúc: Despite/In spite of + N/Np/V-ing, S + V + ... (Clause)

`=>` Although + Clause, Clause 

`-` Vì vế trước V (went) chia ở thì QKD `=>` Vế sau cũng vậy (was)