Open brackets using passive or active voice. 1.he said that grandmother’s letter (to receive) the day before. 2.two new engineers just (to introduce) to the head of the department. 3.we (to finish) this work in time. 4.they (to build) this house in 2001. 5.they (to sell) new children’s books at that shop when i entered it yesterday.

1 had been received
2 have just been introduced
3 will finish
4 built
5 were selling

1. he said that grandmother's letter had been received the day before.
Explanation: In this sentence, the verb "to receive" is in the active voice. To change it to the passive voice, we use the past participle form of the verb ("received") with the auxiliary verb "had been" before it.
Step 1: Identify the verb in the sentence - "to receive"
Step 2: Change the verb to its past participle form - "received"
Step 3: Add the auxiliary verb "had been" before the past participle - "had been received"

2. Two new engineers have just been introduced to the head of the department.
Explanation: In this sentence, the verb "to introduce" is in the active voice. To change it to the passive voice, we use the past participle form of the verb ("introduced") with the auxiliary verb "have been" before it.
Step 1: Identify the verb in the sentence - "to introduce"
Step 2: Change the verb to its past participle form - "introduced"
Step 3: Add the auxiliary verb "have been" before the past participle - "have been introduced"

3. This work will be finished by us in time.
Explanation: In this sentence, the verb "to finish" is in the active voice. To change it to the passive voice, we use the past participle form of the verb ("finished") with the auxiliary verb "will be" before it.
Step 1: Identify the verb in the sentence - "to finish"
Step 2: Change the verb to its past participle form - "finished"
Step 3: Add the auxiliary verb "will be" before the past participle - "will be finished"

4. This house was built in 2001.
Explanation: In this sentence, the verb "to build" is in the active voice. To change it to the passive voice, we use the past participle form of the verb ("built") with the auxiliary verb "was" before it.
Step 1: Identify the verb in the sentence - "to build"
Step 2: Change the verb to its past participle form - "built"
Step 3: Add the auxiliary verb "was" before the past participle - "was built"

5. New children's books were being sold at that shop when I entered it yesterday.
Explanation: In this sentence, the verb "to sell" is in the active voice. To change it to the passive voice, we use the past participle form of the verb ("sold") with the auxiliary verb "were being" before it.
Step 1: Identify the verb in the sentence - "to sell"
Step 2: Change the verb to its past participle form - "sold"
Step 3: Add the auxiliary verb "were being" before the past participle - "were being sold"

Please note that the choice between active and passive voice depends on the context and the focus you want to give to the subject or the object of the sentence.