Exercise 3

`1.` was sitting - saw

`2.` went - was shining

`3.` went - was having

`4.` rained - was carrying

`5.` were walking - began

Trong quá khứ, hành động đang xảy ra chia thì quá khứ tiếp diễn, hành động khác chen vào chia thì quá khứ đơn 

Exercise 4

`1.` saw ( yesterday → dấu hiệu nhận biết thì quá khứ đơn )

`2.` Have you ever bought ( ever → dấu hiệu nhận biết thì hiện tại hoàn thành )

`3.` had ( last winter → dấu hiệu nhận biết thì quá khứ đơn )

`4.` drove ( ago → dấu hiệu nhận biết thì quá khứ đơn )

`5.` ran ( last week → dấu hiệu nhận biết thì quá khứ đơn )

Exercise 3: 

`1.` was sitting, saw

`2.` went, was shining

`3.` went, was having

`4.` was raining, carried

`5.` were walking, began

Hành động đang xảy ra trong quá khứ → QKTD

Hành động chen vào → QKĐ

*Cấu trúc thì quá khứ tiếp diễn:

(+) S + was/ were + V_ing

(- ) S + was/ were + not + V_ing

(? ) Was/ Were + S + V_ing?

*Cấu trúc thì quá khứ đơn:

(+) S + V_ed/ V2

(- ) S + didn't+ V_inf

(? ) Did + S + V_inf?

Exercise 4: 

`1.` saw

yesterday → QKĐ

`2.` Have you ever buy

ever → HTHT

`3.` had

last winter → QKĐ

`4.` drove

A few days → QKĐ

`5.` ran

Last week → QKĐ

*Cấu trúc thì hiện tại hoàn thành:

(+) S + has/ have + V_ed/ V3

(- ) S + has/ have + not + V_ed/ V3

(? ) Has/ Have + S + V_ed/ V3?