**Rule**: For interrogative sentences starting with a 'Wh-' word (like Why, What, When) in the Simple Past Tense, the passive structure is **Wh- word + was/were + object + V3 + by + subject?** - **Correct Answer (a)**: The 'Wh-' word 'Why' remains at the beginning. The object 'such a good opportunity' is singular, so 'was' is used. The past participle of 'waste' is 'wasted'. - **Incorrect Answer (b)**: This option incorrectly changes the tense to Simple Present. - **Incorrect Answer (c)**: This option incorrectly changes the tense to Present Perfect. - **Incorrect Answer (d)**: This option incorrectly changes the tense to Past Perfect.

**Rule**: For a sentence in the Past Perfect Tense, the passive voice structure is **Object + had + been + V3 + by + Subject**. - **Correct Answer (b)**: The object 'many houses' becomes the subject. The verb form 'had been damaged' is the correct passive construction for the Past Perfect Tense. - **Incorrect Answer (a)**: This incorrectly changes the tense to Simple Past. - **Incorrect Answer (c)**: This incorrectly changes the tense to Present Perfect. - **Incorrect Answer (d)**: This incorrectly changes the tense to Past Continuous.

**Rule**: For sentences with modal verbs (like must), the passive structure is **Object + modal verb + be + V3**. The agent 'by you' is often omitted when it is implied or understood. - **Correct Answer (a)**: The object 'This report' becomes the subject. The modal 'must' is followed by 'be' and the past participle 'finished'. The agent 'by you' is correctly omitted. - **Incorrect Answer (b)**: Using 'should' changes the modal from one of strong obligation to one of advice. - **Incorrect Answer (c)**: 'must have been' is the passive form for a past modal, which changes the tense and meaning. - **Incorrect Answer (d)**: 'is to be' implies a plan, which is a different nuance from the obligation of 'must', and the double 'by' phrase is awkward.

**Rule**: When the active sentence uses structures like 'has to' or 'have to', the passive form is **Object + has/have to + be + V3**. - **Correct Answer (c)**: The object 'this work' becomes the subject. Since 'work' is singular, it takes 'has to be', followed by the past participle 'done'. - **Incorrect Answer (a)**: 'is to be' implies a plan or arrangement, which is different from the obligation expressed by 'have to'. - **Incorrect Answer (b)**: 'has been done' is the passive form of the Present Perfect Tense, not of 'have to'. - **Incorrect Answer (d)**: 'had to be' incorrectly changes the tense to the past.

**Rule**: To convert an interrogative sentence in the Past Perfect Tense to passive voice, the structure is **Had + object + been + V3 + by + subject?** - **Correct Answer (a)**: The helping verb 'Had' remains at the beginning. The object 'the task' follows, then 'been' and the past participle 'finished'. - **Incorrect Answer (b)**: This incorrectly changes the tense to Simple Past. - **Incorrect Answer (c)**: This incorrectly changes the tense to Present Perfect. - **Incorrect Answer (d)**: This is not in the correct interrogative word order.

**Rule**: Imperative sentences that express a command are often converted to passive voice using the structure: **Let + object + be + V3**. - **Correct Answer (c)**: This option correctly applies the 'Let' structure for a direct command. 'the window' is the object, followed by 'be' and the past participle 'opened'. - **Incorrect Answer (a)**: 'Should' introduces a sense of advice or obligation, changing the tone from a command. - **Incorrect Answer (b)**: While 'You are ordered to' is a possible passive form, the 'Let' structure is a more common and direct conversion for this type of command. - **Incorrect Answer (d)**: This structure ('is to be') implies a plan or an arrangement, not a direct command.

**Rule**: Certain verbs, especially those expressing feelings or emotions, take prepositions other than 'by' in the passive voice. The verb 'surprised' is typically followed by **'at'** (or sometimes 'by'). The active sentence is in the Simple Past. - **Correct Answer (c)**: The object 'me' becomes 'I'. The verb form 'was surprised' is correct for the Simple Past. The preposition 'at' is idiomatically correct with 'surprised' in this context. - **Incorrect Answer (a)**: While 'by' is sometimes used, 'at' is generally preferred for the source of surprise. - **Incorrect Answer (b)**: This incorrectly changes the tense to Simple Present. - **Incorrect Answer (d)**: This incorrectly changes the tense to Simple Present.

**Rule**: Negative imperative sentences expressing a command can be converted to passive voice using structures like **'You are ordered/forbidden/advised not to...'** or **'Let + object + not + be + V3'**. - **Correct Answer (b)**: 'Do not make a noise' is a direct command. Therefore, 'You are ordered not to make a noise' is a very appropriate passive construction. - **Incorrect Answer (a)**: 'Requested' is incorrect as the original sentence is a command, not a request. - **Incorrect Answer (c)**: This is also a possible passive form, but option (b) is equally valid and often more direct in conveying the command. - **Incorrect Answer (d)**: 'Should' introduces a sense of advice, which is weaker than the command in the original sentence.

**Rule**: When a verb in the active voice is followed by a preposition (a phrasal verb), the preposition must be retained in the passive voice. The structure for Simple Past is **Object + was/were + V3 + preposition + by + Subject**. - **Correct Answer (c)**: The object 'the beggar' becomes the subject. The verb form 'was laughed at' correctly keeps the preposition 'at' with the verb. - **Incorrect Answer (a)**: The preposition 'at' is incorrectly omitted. - **Incorrect Answer (b)**: This incorrectly changes the tense to Past Continuous. - **Incorrect Answer (d)**: The second preposition 'at' is incorrect; 'by' is needed to introduce the agent.

**Rule**: For a Future Simple Tense sentence, the passive structure is **Object + will/shall + be + V3**. Conventionally, 'shall' is used with the first person pronouns 'I' and 'we' in formal future tense, while 'will' is used for second and third person. However, 'will' is now commonly used for all persons. - **Correct Answer (b)**: The object 'me' becomes the subject 'I'. Following traditional grammar rules, 'shall' is the most appropriate auxiliary verb with 'I' in the future tense, followed by 'be' and the past participle 'obliged'. - **Incorrect Answer (a)**: While 'will' is widely accepted with 'I' in modern English, 'shall' is considered more formally correct. - **Incorrect Answer (c)**: 'would' is an incorrect modal change. - **Incorrect Answer (d)**: This incorrectly changes the tense to Simple Present.