1. The incident (to happen) the other day.

2. Her name was Helen. She (to be) a widow for fifteen years

and had no children.

3. When we (to leave) home, the rain already (to stop).

4. When I (to graduate) from the University my elder brother

(to work) for a foreign company for two years.

5. Yesterday I (to find) a book I (to look for) so long.

6. When you (to go) to the cinema last?

7. They (to live) in Canada for a few years and then (to move)

to Australia.

8. You (to wait) for half an hour before the taxi came.

9. All night long the stars (to glitter).

10. What you (to do) when I (to come in)?

11. When I (to leave) the university, it (to rain) heavily.

12. When John (to return) home, he (to see) his younger

brother who (to do) his homework.

13. Nick said that he (to write) all day and (not to eat) anything.

14. We (to work) in the garden for some hours when it began

to rain.

15. I (to see) Irene yesterday at the stores: she and Mr. Smith

(to have) a nice little talk.

16. Robert (to talk) to some of the other guests when Nick

(to come in).

17. She hoped I (to pay) for the tickets.

18. When we (to come) the plane (to take off).

19. By the end of last month they (not to complete) the experiment yet.

20. Ann’s grandfather (to found) his firm in 1901.

1. The incident happened the other day.
Explanation: The verb "to happen" is conjugated in the past simple tense.
Step-by-step solution: The base form of the verb "to happen" is "happen". To change it to the past simple tense, we add "-ed" to the end of the verb, resulting in "happened".

2. Her name was Helen. She had been a widow for fifteen years and had no children.
Explanation: The verb "to be" is conjugated in the past simple tense, and the verb "to have" is conjugated in the past perfect tense.
Step-by-step solution: We simply change the verb "to be" to its past simple form, which is "was". To form the past perfect tense of the verb "to have", we use "had" followed by the past participle of the main verb, in this case, "been".

3. When we left home, the rain had already stopped.
Explanation: The verb "to leave" is conjugated in the past simple tense, and the verb "to stop" is conjugated in the past perfect tense.
Step-by-step solution: We change the verb "to leave" to its past simple form, which is "left". To form the past perfect tense of the verb "to stop", we use "had" followed by the past participle of the main verb, which is "stopped".

4. When I graduated from the University, my elder brother had been working for a foreign company for two years.
Explanation: The verb "to graduate" is conjugated in the past simple tense, and the verb "to work" is conjugated in the past perfect continuous tense.
Step-by-step solution: We change the verb "to graduate" to its past simple form, which is "graduated". To form the past perfect continuous tense of the verb "to work", we use "had been" followed by the present participle of the main verb, which is "working".

5. Yesterday I found a book I had been looking for so long.
Explanation: The verb "to find" is conjugated in the past simple tense, and the verb "to look" is conjugated in the past perfect continuous tense.
Step-by-step solution: We change the verb "to find" to its past simple form, which is "found". To form the past perfect continuous tense of the verb "to look", we use "had been" followed by the present participle of the main verb, which is "looking".

6. When did you go to the cinema last?
Explanation: The verb "to go" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to go" to its past simple form, which is "went".

7. They had lived in Canada for a few years and then moved to Australia.
Explanation: The verb "to live" is conjugated in the past perfect tense, and the verb "to move" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to live" to its past perfect form, which is "had lived". We also change the verb "to move" to its past simple form, which is "moved".

8. You had waited for half an hour before the taxi came.
Explanation: The verb "to wait" is conjugated in the past perfect tense.
Step-by-step solution: We change the verb "to wait" to its past perfect form, which is "had waited".

9. All night long, the stars were glittering.
Explanation: The verb "to glitter" is conjugated in the past continuous tense.
Step-by-step solution: We change the verb "to glitter" to its past continuous form, which is "were glittering".

10. What were you doing when I came in?
Explanation: The verb "to do" is conjugated in the past continuous tense, and the verb "to come in" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to do" to its past continuous form, which is "were doing". We also change the verb "to come in" to its past simple form, which is "came in".

11. When I left the university, it was raining heavily.
Explanation: The verb "to leave" is conjugated in the past simple tense, and the verb "to rain" is conjugated in the past continuous tense.
Step-by-step solution: We change the verb "to leave" to its past simple form, which is "left". We also change the verb "to rain" to its past continuous form, which is "was raining".

12. When John returned home, he saw his younger brother who was doing his homework.
Explanation: The verb "to return" and "to see" are conjugated in the past simple tense, and the verb "to do" is conjugated in the past continuous tense.
Step-by-step solution: We change the verb "to return" to its past simple form, which is "returned". We also change the verb "to see" to its past simple form, which is "saw". We change the verb "to do" to its past continuous form, which is "was doing".

13. Nick said that he had been writing all day and had not eaten anything.
Explanation: The verb "to write" is conjugated in the past perfect continuous tense, and the verb "to eat" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to write" to its past perfect continuous form, which is "had been writing". We also change the verb "to eat" to its past simple form, which is "had not eaten".

14. We had been working in the garden for some hours when it began to rain.
Explanation: The verb "to work" is conjugated in the past perfect continuous tense, and the verb "to rain" is also conjugated in the past simple tense.
Step-by-step solution: We change the verb "to work" to its past perfect continuous form, which is "had been working". We also change the verb "to rain" to its past simple form, which is "began to rain".

15. I saw Irene yesterday at the stores: she and Mr. Smith were having a nice little talk.
Explanation: The verb "to see" and "to have" are conjugated in the past simple tense.
Step-by-step solution: We change the verb "to see" to its past simple form, which is "saw". We also change the verb "to have" to its past simple form, which is "were having".

16. Robert was talking to some of the other guests when Nick came in.
Explanation: The verb "to talk" is conjugated in the past continuous tense, and the verb "to come in" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to talk" to its past continuous form, which is "was talking". We also change the verb "to come in" to its past simple form, which is "came in".

17. She hoped I would pay for the tickets.
Explanation: The verb "to pay" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to pay" to its past simple form, which is "would pay".

18. When we came, the plane took off.
Explanation: The verb "to come" is conjugated in the past simple tense, and the verb "to take off" is also conjugated in the past simple tense.
Step-by-step solution: We change the verb "to come" to its past simple form, which is "came". We also change the verb "to take off" to its past simple form, which is "took off".

19. By the end of last month, they had not yet completed the experiment.
Explanation: The verb "to complete" is conjugated in the past simple tense, and the verb "to not" is used to indicate negation.
Step-by-step solution: We change the verb "to complete" to its past simple form, which is "completed". We also add the word "not" before the verb to indicate negation.

20. Ann’s grandfather founded his firm in 1901.
Explanation: The verb "to found" is conjugated in the past simple tense.
Step-by-step solution: We change the verb "to found" to its past simple form, which is "founded".