8use past simple or present perfect to complete the sentences. 1 the concert (just begin) has just begun. 2 sam (phone) just now. 3 the boys were so hungry. they (eat) all the sandwiches and (ask) for more. 4 our children (already become) grown-ups. 5 the fridge is empty. i can see that bob (not be) to the shops. 6 the other day we (write) to them, but we (not receive) any answer so far. 7 alex, what present (you choose) for daddy? 8 simon (not get) any bad marks recently. his teacher says the boy (change) a lot. 9 last tuesday they (drive) to oxford in their ford. the journey (not be) long at all. it (take) them about two hours and a half. 10 it’s the second time i (ride) a horse.

1. The concert has just begun.
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, the concert has just started, so it is still ongoing and has a connection to the present moment.

2. Sam has just phoned now.
Explanation: We use the present perfect tense to talk about a past action that has a connection to the present. In this sentence, Sam made a phone call in the recent past, which has a connection to the present moment.

3. The boys were so hungry. They have eaten all the sandwiches and have asked for more.
Explanation: We use the present perfect tense when an action happened in the past but has a connection to the present. In this sentence, the boys ate all the sandwiches in the past and have asked for more, which shows a connection to the present moment.

4. Our children have already become grown-ups.
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, the action of our children becoming grown-ups happened in the past, but it has a connection to the present moment.

5. The fridge is empty. I can see that Bob has not been to the shops.
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, Bob did not go to the shops in the past, and this has a connection to the present situation of the fridge being empty.

6. The other day, we wrote to them, but we have not received any answer so far.
Explanation: We use the past simple tense to talk about a completed action in the past. In this sentence, we wrote to them in the past, and it is a completed action. However, we use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, we have not received any answer, which shows a connection to the present moment.

7. Alex, what present have you chosen for daddy?
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, the action of choosing a present for daddy happened in the past, but it has a connection to the present moment.

8. Simon has not got any bad marks recently. His teacher says the boy has changed a lot.
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, Simon did not get any bad marks in the recent past, and this has a connection to the present moment. Additionally, his teacher says that Simon has changed a lot, which also shows a connection to the present.

9. Last Tuesday, they drove to Oxford in their Ford. The journey was not long at all. It took them about two and a half hours.
Explanation: We use the past simple tense to talk about completed actions in the past. In this sentence, last Tuesday, they drove to Oxford, which is a completed action. Additionally, we use the past simple tense to talk about the length of the journey, which is also a completed action.

10. It is the second time I have ridden a horse.
Explanation: We use the present perfect tense to talk about an action that happened in the past but has a connection to the present. In this sentence, the action of riding a horse happened in the past, but it has a connection to the present moment, as it is the second time the person has ridden a horse.