`12` was - had been

`=>` S + V2/ed + until + S + had past participle

`=>` ago `->` QKĐ

`=>` until 2 months ago `->` QKHT

`13` broken

`=>`Thì QKĐ: Với động từ thường: S + V2/ed

`=>` DHNB: the day before her exam

`14` catches

`=>` every winter: thì HTĐ

`15` did he travel

`=>` yesterday: thì QKĐ

`16` was waiting - was waiting

`=>` S +was/were+V-ing, while S + was/were+V-ing

`=>`  nói về những hành động xảy ra liên tiếp, có thể diễn ra trong 1 khoảng thời gian

`17`  was leaving

`=>` S + was/were + V-ing + when + S + V-ed/V2

`18` didn't see

`=>` last monday: thì QKĐ

`19`sailed

`=>` ago `->` QKĐ

`=>` S+Ved-2

`20` will leave / knows 

`=>` I think: tôi nghĩ `->` thì TLĐ

`=>` S+will+V

`=>` Vế sau là HTĐ: S+Vs/es

`21` was rainning - decided

`=>` last week: quá khứ đơn

`=>`Vế đầu là QKTD `->` `(+)` S + was/were + V-ing

`=>` Vế sau là QKĐ `->` `(+)` S+Ved/2

`12)`

`to` was `-` had been

`-` Có ago `to` QKĐ

`( + )` S + Was/were + O

`-` Có until `2` months ago `to` QKHT

`( + )` S + had + Ved/ Cột `3`

`13)` 

`to` Had broken

`-` Before her exam `to` QKHT

`14)`

`to` catches

`=` Có every winter `to` HTĐ

`( + )` S + Vs/es + O

`-` S là số tí `to` Vs

`15)`

`to` Did he travel

`-` Có yesterday `to` QKĐ

`-` WH + did + S + V + O `?`

`16)`

`to` was waiting `-` was waiting

`-` Hành động diễn ra song song `to` QKTD

`17)`

`to` was leaving

`-` S + QKTD + when + S + QKĐ

`18)`

`to` didn't see

`-` Có last Monday `to` QKĐ

`( - )` S + did not + V(nt) + O

`19)`

`to` sailed

`-` Có ago `to` QKĐ

`20)`

`to` will leave`-` knows

`-` I think + TLĐ

`-` HTĐ: S + Vs/es + O

`-` Vì S là số ít `to` Vs

`21)`

`to` Was raining `-` decided

`-` Có last week `to` QKĐ

`-` Decided + to V: quyết định làm việc gì đó

`#Ph`