`1` were building - dấu hiệu : at this time last year 

`2` was driving 

`3` chatted - was teaching

`4` was watching

`5` was preparing - dấu hiệu : at this time yesterday

`6` were you doing - dấu hiệu : at 8pm yesterday 

`7` were you going

`8` weren't going

`9` wasn't doing

`10` read - was playing 

`->` Thì Quá Khứ Tiếp Diễn

`-` S + was/were + V-ing + O 

`-` S + was/were + not + V-ing + O 

`-` Was/were + S + V-ing + O ? 

`+` S + was/were + V-ing +  O + when + S + Ved/V2 +  O

`+` S + Ved/V2 + O + while + S + was/were + V-ing + O 

`+` Use : 

`-` Diễn tả 1 sự việc hay hành động đang xảy ra tại 1 thời điểm xác định trong quá khứ

`-` Diễn tả 1 sự việc đang xảy ra trong quá khứ tại 1 thời điểm xác định thì 1 sự việc khác xen vào

`-` Diễn tả 2 sự việc đang xảy ra song song với nhau tại 1 thời điểm xác định trong quá khứ 

`1.` were building

`2.` was driving

`3.` was chatting - was teaching

`4.` was watching

`5.` was preparing

`6.` What was you doing at 8 pm yesterday ?

`7.` Where was you doing when I saw you last weekend ?

`8.` weren't going

`9.` wasn't doing

`10.` wasn't reading - wasn't playing

Cấu trúc :

`(+)` S `+` was/were `+` V-ing `+` O

`(-)` S `+` was/were `+` not `+` V-ing `+` O

`(?)` Was/Were `+` S + V-ing + O ?

  Yes , S `+` was/were

  No , S `+` was/were `+` not