`1.` put

`2.` didn't disturb 

`3.` didn't hold

`4.` decided

`5.` didn't sleep

`6.` didn't like

`7. `didn't cost

`8.` didn't have

`9.` wasn't 

`10.` stayed

`---------------`

`2.` They also help people rebuild houses and plant trees.

`3.` Many generous people donated money for poor people.

`4.` When I was a student, I often joined in charitable work.

`5.` I used to travel to remoted area with my friends to help people there.

`6.` We stay in the mountainous area for weeks.

`7.` We taught the children there to read and write.

`8.` Being a volunteer was a wonderful experience.

`9.` After I graduated, I was very busy.

`10.` Now I still do charity in my hometown.

`@` Quá khứ đơn :

`-` Tobe : 

`( + )` S + was / were + N / adj.

`( - )` S + was / were + not + N / adj.

`( ? )` Was / Were + S + N / adj`?`

`+)` I / she / he / it / danh từ số ít + was

`+)` You / we / they / danh từ số nhiều + were 

`-` Verb : 

`( + )` S + Ved / V2.

`( - )` S + didn't + V`-`infi.

`( ? )` Did + S + V`-`infi `?`

`-` Cách dùng : 

`->` Thì quá khứ đơn diễn tả một hành động đã xảy ra trong quá khứ, đã kết thúc rồi và biết rõ thời gian.

`->` Thì quá khứ đơn diễn tả một hành động đã xảy ra liên tiếp trong suốt một khoảng thời gian trong quá khứ nhưng hiện tại đã hoàn toàn chấm dứt.

`->` Thì quá khứ đơn diễn tả một hành động xen vào một hành động khác trong quá khứ.

`-` `DHNB`:

`+` yesterday.

`+` last + time.

`+` time + ago.