Question

Pick the option that turns the sentence passive. Something _____ happened or they would be here by now.

• A. must be
• B. must have
• C. must
• D. must have been

Answer 1

Answer:

B. must have

Here, must have + past participle (V3) is used to express a strong deduction about something that happened in the past.

• must have happened = it is almost certain that something happened.

Happen is an intransitive verb, so it cannot normally be changed into the passive voice. Therefore, this question is actually testing the correct modal perfect form, not passive voice.

Options

• ❌ must be → means something is necessary/expected to be in a state now.

• ❌ must → incomplete; needs a suitable verb after it.

• ❌ must have been → would require a complement or a past participle, e.g., must have been delayed.

• ✅ must have → followed by happened → must have happened.