Đáp án:

`14.`

 live - lived

 start - started

 play - played

 find - found

 bring - brought

 permit - permitted

 break - broke

 lose - lost

 carry - carried

 study - studied

 try - tried

 pay - paid

 stop - stopped

 be - was / were

 make - made

 enjoy - enjoyed

 buy - bought

 have - had

 send - sent

 give - gave

 sit - sat

 begin - began

 hold - held

 build - built

 go - went

 tell - told

 speak - spoke

 meet - met

 watch - watched

 work - worked

 hear - heard

 prepare - prepared

 read - read

 know - knew

 tell - told

 write - wrote

 can - could 

 leave - left

 do - did

 encourage - encouraged

 arrive - arrived

 believe - believed

 take - took

 come - came

 teach - taught

 sing - sang

 learn - learned / learnt

`15.`

`1.` They didn't watch a good football match on TV last night.

`2.` Peter didn't send that letter to Marry yesterday morning.

`3.` Jane's mother didn't buy a new car last month.

`4.` We didn't visit Ha Long Bay three years ago.

`5.` They didn't leave for Hai Phong in `1999`.

`6.` They didn't build a new school in my village ten months ago.

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

`8.` We didn't buy a house near Thao's house in `2009.`

_________________________________________________________________________

 Thì QKĐ:

`( + )`  S + V2 / Ved 

`( - )`  S + didn't + V

`(  ?  )`  Did + S + V ?