**Rule**: A negative sentence with a past modal (modal + have + V3) is converted to passive using **Object + modal + not + have been + V3**. The negative idea from 'Nobody' is transferred to the verb.

- **Correct Answer (b)**: The object 'this outcome' becomes the subject. The past modal passive form 'could not have been predicted' is the correct negative construction. The agent is correctly omitted.
- **Incorrect Answer (a)**: This incorrectly changes the structure to a simple past passive.
- **Incorrect Answer (c)**: 'could not be predicted' is the passive form for a present modal ('could not predict'), not a past modal.
- **Incorrect Answer (d)**: 'cannot' is a different modal and is not the correct conversion of 'could not'.

**Rule**: When the active sentence uses 'has to' to show necessity, the passive form is **Object + has/have to + be + V3**.

- **Correct Answer (b)**: The object 'the next game' becomes the subject. Since 'game' is singular, it takes 'has to be', followed by the past participle 'won'.
- **Incorrect Answer (a)**: 'has been won' is the passive of the Present Perfect Tense.
- **Incorrect Answer (c)**: 'had to be' incorrectly changes the tense to the past.
- **Incorrect Answer (d)**: 'is to be' implies a plan, which is a different meaning.

**Rule**: When the active sentence uses 'has to' to show necessity, the passive form is **Object + has/have to + be + V3**.

- **Correct Answer (d)**: The object 'a new logo' becomes the subject. Since 'logo' is singular, it takes 'has to be', followed by the past participle 'designed'.
- **Incorrect Answer (a)**: 'has been designed' is the passive of the Present Perfect Tense.
- **Incorrect Answer (b)**: 'had to be' incorrectly changes the tense to the past.
- **Incorrect Answer (c)**: This incorrectly changes the tense to the future.

**Rule**: For a Simple Past Tense sentence with two objects (indirect 'me' and direct 'a headache'), either can become the subject of the passive sentence.

- **Correct Answer (d)**: Both (a) and (b) are correct passive transformations.
- In (a), the direct object 'A headache' becomes the subject. The passive verb is 'was given', and the indirect object 'me' is preceded by 'to'.
- In (b), the indirect object 'me' becomes the subject 'I'. The passive verb is 'was given', and the direct object 'a headache' follows.
- **Incorrect Answer (a)**: This is correct, but (b) is also a valid transformation.
- **Incorrect Answer (b)**: This is correct, but (a) is also a valid transformation.
- **Incorrect Answer (c)**: This incorrectly changes the tense to Present Perfect.

**Rule**: When the active sentence uses 'will have to' with a phrasal verb, the passive form is **Object + will have to + be + V3 + particle**.

- **Correct Answer (d)**: The object 'some workers' becomes the subject. The structure 'will have to be laid off' is the correct passive form for the future necessity, keeping the particle 'off' with the verb.
- **Incorrect Answer (a)**: This omits 'have to', changing the meaning.
- **Incorrect Answer (b)**: This is the passive of the Future Perfect Tense.
- **Incorrect Answer (c)**: 'would' is an incorrect modal change.

**Rule**: For a negative sentence in the Past Continuous Tense, the passive structure is **Object + was/were + not + being + V3 + by + Subject**.

- **Correct Answer (d)**: The object 'the students' becomes the subject. The passive verb form 'were not being helped' correctly reflects the negative Past Continuous tense.
- **Incorrect Answer (a)**: This incorrectly changes the tense to Simple Past.
- **Incorrect Answer (b)**: This incorrectly changes the tense to Present Perfect.
- **Incorrect Answer (c)**: This incorrectly changes the tense to Present Continuous.

**Rule**: For an interrogative sentence in the Simple Past Tense starting with 'Which', the passive structure is **Which + noun + was/were + V3 + by + subject?**

- **Correct Answer (d)**: 'Which book' remains at the beginning. As 'book' is singular, it is followed by 'was' and the past participle 'chosen'.
- **Incorrect Answer (a)**: This incorrectly changes the tense to Simple Present.
- **Incorrect Answer (b)**: This incorrectly changes the tense to Present Perfect.
- **Incorrect Answer (c)**: This incorrectly changes the tense to Past Continuous.

**Rule**: For an interrogative sentence with the 'be going to' future form starting with 'Who', the passive structure is **By whom + is/am/are + object + going to be + V3?**

- **Correct Answer (c)**: 'Who' changes to 'By whom'. The object 'the computer' is singular, so 'is' is used, followed by the object and the correct passive structure 'going to be fixed'.
- **Incorrect Answer (a)**: This changes the structure to the 'will' future.
- **Incorrect Answer (b)**: 'who' is the incorrect case; 'whom' is required after the preposition 'By'.
- **Incorrect Answer (d)**: This word order is not standard for formal interrogative sentences.

**Rule**: When the active sentence uses 'has to' to show necessity, the passive form is **Object + has/have to + be + V3**.

- **Correct Answer (c)**: The object 'the final design' becomes the subject. Since 'design' is singular, it takes 'has to be', followed by the past participle 'approved'.
- **Incorrect Answer (a)**: 'has been approved' is the passive of the Present Perfect Tense.
- **Incorrect Answer (b)**: 'had to be' incorrectly changes the tense to the past.
- **Incorrect Answer (d)**: 'is to be' implies a plan, not necessity.

**Rule**: For a negative sentence in the Past Perfect Tense, the passive structure is **Object + had + not + been + V3 + by + Subject**.

- **Correct Answer (c)**: The object 'the project' becomes the subject. The verb form 'had not been finished' is the correct passive construction for a negative sentence in the Past Perfect Tense.
- **Incorrect Answer (a)**: This incorrectly changes the tense to Simple Past.
- **Incorrect Answer (b)**: This incorrectly changes the tense to Present Perfect.
- **Incorrect Answer (d)**: 'being' is incorrect; the past participle 'been' is required.