Select the option that expresses the given sentence in passive voice. We should clean the house regularly.

Correct — A. The active verb is should clean — a modal followed by a bare infinitive.

The passive of a modal has one fixed shape: modal + be + past participle. So 'should clean' becomes should be cleaned.

The object, the house, moves to the front as subject; the subject, we, goes into the by-phrase as 'by us'; 'regularly' stays beside the verb.

That gives 'The house should be cleaned regularly by us' — option (a).

Why the others are wrong

• (b)
  The house should be being cleaned regularly by us. — should be being cleaned is a modal continuous passive. The active sentence is simple, not continuous, so there is no -ing form to carry across, and the string is unusable in ordinary writing.
• (c)
  The house should be clean regularly by us. — In 'should be clean', clean is the adjective, not the past participle. It describes a state the house is in rather than the act of cleaning it, which is what the sentence is about.
• (d)
  The house should have been cleaned regularly by us. — should have been cleaned is the passive of 'should have cleaned' — a duty that was not discharged in the past. The printed sentence states a standing obligation, not a missed one.

A modal has no tense of its own and always takes a bare infinitive, so its passive is built in one fixed shape: modal + be + past participle.

should clean becomes should be cleaned. must deliver becomes must be delivered. will play becomes will be played.

The modal itself never changes; only what follows it does. That is why should have been cleaned is a different sentence rather than a more formal one — the perfect reports an obligation already missed.

An adverb of frequency such as regularly keeps its place beside the verb, and the by-phrase follows it.

Key facts

• The passive of a modal is modal + be + past participle, so 'should clean' becomes 'should be cleaned'.
• 'Should have been cleaned' is the passive of 'should have cleaned' and reports an unmet past duty.
• In 'The house should be clean', clean is an adjective describing a state, not a passive verb.

Common traps

• Adding 'being' to make the passive look complete, which produces 'should be being cleaned'.
• Accepting 'should be clean' because it is a real English sentence, though it means something else.
• Reaching for 'should have been cleaned' because the perfect form sounds more formal.

No directly related past PYQ was found.