Open the brackets. Use Past Indefinite or Past Perfect. 1.Mother (to buy) a new vacuum cleaner after she (to see) its advertisement on TV.
2. We (to learn) about this entertainmert centre after we (to watch) a film about it.
3. Dad (to phone) the company after he (to find) its contacts in the Internet.
4. Before we (to visit) the exhibition, we (to read) about it in the magazine.
5. The journalists (to collect) the information about the new sports centre by last Friday.
6. When the sportsmen (to arrive) in London the weather already (to change).
7. When I (to meet) this writer, he already (to become) famous in the world.

1. Mother bought a new vacuum cleaner after she saw its advertisement on TV.
In this sentence, we use the Past Indefinite tense for both actions. "Bought" is the simple past form of the verb "to buy," and "saw" is the simple past form of the verb "to see." We use the Past Indefinite tense to talk about completed actions in the past.

2. We learned about this entertainment centre after we watched a film about it.
Again, we use the Past Indefinite tense for both actions. "Learned" is the simple past form of the verb "to learn," and "watched" is the simple past form of the verb "to watch."

3. Dad phoned the company after he found its contacts on the Internet.
In this sentence, we use the Past Indefinite tense for both actions. "Phoned" is the simple past form of the verb "to phone," and "found" is the simple past form of the verb "to find."

4. Before we visited the exhibition, we read about it in the magazine.
Here, we use the Past Indefinite tense for both actions. "Visited" is the simple past form of the verb "to visit," and "read" is the simple past form of the verb "to read."

5. The journalists collected the information about the new sports centre by last Friday.
In this sentence, we use the Past Indefinite tense for the first action and the Past Perfect tense for the second action. "Collected" is the simple past form of the verb "to collect," while "had collected" is the past perfect form. We use the Past Perfect tense to express an action that happened before another action in the past.

6. When the sportsmen arrived in London, the weather had already changed.
Here, we use the Past Indefinite tense for the first action and the Past Perfect tense for the second action. "Arrived" is the simple past form of the verb "to arrive," and "had changed" is the past perfect form. Again, we use the Past Perfect tense to show that one action happened before another action in the past.

7. When I met this writer, he had already become famous in the world.
We use the Past Indefinite tense for the first action and the Past Perfect tense for the second action. "Met" is the simple past form of the verb "to meet," and "had become" is the past perfect form. The Past Perfect tense emphasizes that the writer became famous before the meeting took place.

In summary, the Past Indefinite tense is used for completed actions in the past, while the Past Perfect tense is used for actions that happened before another action in the past.