$1$. took

$2$. arrived - weren't

$3$. sold - bought

$4$. taught

$5$. started - was

$6$. donated

$7$. rang - invited

$8$. Did you watch

$9$. was - used to

$10$. Did you go

$11$. wasn't - didn't feel

$12$. spent

$13$. wrote - didn't write

$14$. Were they

$15$. saw

*Đề bài bảo điền QKD

$-$ CT thì QKD:

$+)$ S + Ved/2

$-)$ S + didn't + V-inf

$?)$ Did + S + V-inf ?

1.took

2.arrived - weren't

3.sold - bought

4.taught

5.started - was

6.donated

7.rang - invited

8.Did you watch

9.was - used to

10.Did you go

11.wasn't - didn't feel

12.spent

13.wrote - didn't write

14.Were they

15.saw

Cấu trúc Quá khứ đơn 

(+) S+V_ed/2

S+was/were

(-) S+didn't+V_bare

S+was/were+not

(?) Did + S + V_bare

Was/were+S+V_bare