1. I haven't gone to the supermarket for three weeks. => The last time__________________________ 2. It took Mary two hours to travel to the countryside last week. => Mary spent______________________________ 3. Durinh the English lesson, the light went out. => While we were__________________________

`1.` The last time I went to the supermarket was three weeks ago.

`-` Cấu trúc: S + haven't/hasn't +VpII + O + for + khoảng thời gian/since + mốc thời gian

`=>` The last time + S + V-ed + O + was + khoảng thời gian + ago/when/in + mốc thời gian 

`2.` Mary spent two hours travelling to the countryside last week. 

`-` Cấu trúc: IT + takes/took + O + time + to V-inf + O

`=>` S + spend(s)/spent + time + V-ing + O

`3.` While we were learning English, the light went out. 

`-` Cấu trúc: While + S +was/were + V-ing + O, S + V-ed + O

`-` Diễn tả một sự việc đang xảy ra thì một sự việc khác chen vào