`Answer:`

`11,`

`(-)` Jane’s mother didn't buy a new car last month.

`(?)` Did Jane's mother buy a new car last month?

`12,`

`(-)` We didn't visit Halong Bay three years ago.

`(?)` Did you visit Halong Bay three years ago?

`13,`

`(-)` They didn't leave for Hai Phong in 1999.

`(?)` Did they leave for Hai Phong in 1999?

`14,`

`(-)` They didn't buy a new school in my village ten month ago.

`(?)` Did they buy a new school in my village ten month ago?

`15,` 

`(-)` I didn't borrow a lot of book in the library last weekend.

`(?)` Did you borrow a lot of book in the library last weekend?

___________________________________________________

$\text{*Past Simple}$

`@` Với ĐT tobe:

`(+)` $\text{S + was/were + O.....}$

`(-)` $\text{S + was/were + not + O.....}$

`(?)` $\text{Was/Were + (not) + S + O......}$

`@` Với ĐT thường:

`(+)` $\text{S + Vpp}$

`(-)` $\text{S + didn't + V}$

`(?)` $\text{Did + (not) + S + V}$

`-` DHNB: yesterday, last (week, month, year, ....), ago, ...

`#TD`

11. (-) Jane’s mother didn't buy a new car last month.  

(?) Did Jane’s mother buy a new car last month?

12. (-) We didn't visit Halong Bay three years ago.  

(?) Did we visit Halong Bay three years ago?

13. (-) They didn't leave for Hai Phong in 1999.  

(?) Did they leave for Hai Phong in 1999?

14. (-) They didn't build a new school in my village ten months ago.  

(?) Did they build a new school in my village ten months ago?

15. (-) I didn't borrow a lot of books in the library last weekend.  

(?) Did I borrow a lot of books in the library last weekend?

---------------------------

Thì quá khứ đơn : 

`@` Động từ thường :

Câu khẳng định: S + V-ed/2

Câu phủ định: S + did not (didn't) + V (động từ nguyên mẫu)

Câu nghi vấn: Did + S + V (động từ nguyên mẫu)?

`@` Tobe : 

Câu khẳng định: S + was/were +N/adj

Câu phủ định: S + was/were not (wasn't/weren't) +N/adj

Câu nghi vấn:Was/Were + S +N/adj?

`@` Dấu hiệu nhận biết :

- Thời điểm cụ thể trong quá khứ:  yesterday, last week, two days ago, in 1990, last year,....

- Diễn tả các hành động hoặc trạng thái đã xảy ra và kết thúc trong quá khứ.