`-` Thì QKĐ :

`+` KĐ : S + Ved / V2 `-` S + was / were + adj / n

`+` PĐ : S + didn't + V `-` S + wasn't / weren't + adj / n

`+` NV : Did + S + V ? `-` Was / Were + S + adj / n ?

`-` Thì QKTD :

`+` KĐ : S + was / were + V-ing

`+` PĐ : S + wasn't / weren't + V-ing

`+` NV : Was / Were + S + V-ing ?

`-` When + S + Ved / V2 , S + was / were + V-ing

`-` While + S + was / were + V-ing , S + Ved / V2

`=>` Dùng để diễn tả về hành động đang diễn ra , hành động chỉ xảy ra `1` lúc

`-` When + S + Ved / V2 , S + Ved / V2

`=>` Dùng để diễn tả về `2` hành động xảy ra trong Quá khứ

`-` While + S + was / were + V-ing , S + was / were + V-ing

`=>` Dùng để diễn tả về `2` hành động đang diễn ra trong Quá khứ

`1`.was playing / entered

`2`.was studying / came

`3`.was washing / rang

`4`.was eating / were drinking

`5`.was watching / jumped

`6`.was studying

`7`.were they doing ?

`8`.taught

`9`.didn't go

`->` `DHNB` : last

`10`.was working

`->` at that time `=` Mốc thời gian mà sự việc đang xảy ra

`=>` Dùng QKTD

`11`.were sitting / drinking

`->` `DHNB` : Yesterday at `9.30` p.m

`12`.was making / cleaning

`->` Hành động đang xảy ra tại mốc thời gian nào đó không xác định

`=>` Dùng QKTD

`13`.was knocking / was reading

`14`.bought / lived

`15`.didn't meet

`->` `DHNB` : last

`16`.was having / went

`\text{# TF}`