Q: I’m puzzled by these two sentences: “The robbers broke into the bank” and “The bank was broken into.” In the active sentence, “bank” isn’t a direct object. Why then is it possible to make it a subject in the passive sentence?
A. Normally, a sentence in the active voice can be made passive by turning the object of the verb into the subject. So “A pickpocket stole his wallet” becomes “His wallet was stolen.” (You can add “by a pickpocket” if you want to say whodunit.)
But you’re right that “bank” in the first sentence isn’t the object of the verb. The word “bank” here is the object of a preposition. And the object of a preposition can be turned into the subject of a passive sentence.
What confuses you here is the word “into.” It’s actually a compound that combines the adverb “in” and the preposition “to.” For purposes of illustration, let’s divide it—“in” (adverb) + “to” (preposition)—to show how its parts function.
Why do this? Because the verb here is not “break.” It’s “break in,” a phrasal verb that incorporates the adverb “in.” And the following “to” introduces the prepositional phrase “to the bank.”
So, with “into” separated, our sentence now looks like this: “The robbers broke in + to the bank.”
In its felonious sense, the phrasal verb “break in” is intransitive—that is, it doesn’t need a direct object. All it needs is a subject to be complete: “Robbers broke in.”
We can’t add a direct object here, because robbers can’t “break in the bank.” If we want to mention the bank, we have to add a prepositional phrase: “break in + to the bank.”
This is true of many phrasal verbs that are intransitive. They don’t have direct objects, so if there’s a complement at all it’s likely to be a prepositional phrase. A few examples of such verbs:
● “look in” (to make a short visit). We don’t “look in the baby” (direct object); we “look in on the baby” (prepositional phrase).
● “make up” (to reconcile). We don’t “make up Gerald”; we “make up with Gerald.”
● “speak out” (to talk forcefully). We don’t “speak out injustice”; we “speak out against injustice.”
● “check in” (to register at a hotel). We don’t “check in the hotel”; we “check in + to [or at] the hotel.”
Usually the adverbial part of a phrasal verb isn’t combined with the following preposition. We don’t “look inon the baby” or “make upwith Gerald.”
But when the parts are “in” and “to,” they’re often combined. (This isn’t always the case, as we’ve written on our blog: “We went in to dinner” … “They tuned in to the program.”)
Which brings us—in a roundabout way—back to your question about how an intransitive verb becomes passive.
With an intransitive verb, as we’ve said, the object of the preposition, not the object of the verb, becomes the passive subject.
You were confused by the phrasal verb “break in.” This is easier to see with an ordinary intransitive verb, like “shout.” It too needs only a subject (“They shouted”), and requires no direct object.
But if there’s a complement in the form of a prepositional phrase (“They shouted at the dog”), we can construct a passive version.
The object of the preposition (“the dog”) now becomes the subject, and the preposition is retained at the end (“The dog was shouted at”).
Sometimes passives derived from intransitive verbs are not idiomatic English: “Gerald was made up with” … “The hotel was checked in at.”
But others are normal and acceptable, like “The baby was looked in on.”
These are sometimes called “prepositional passives.” And as The Cambridge Grammar of the English Language says, “they are not admissible in all cases.”
Cambridge gives these examples of acceptable ones: “This bed has been slept in” … “Her book was referred to” … “These matters must be seen to.”
And it gives these as unacceptable: “Boston was flown to next” … “Such principles were stood for” … “Some old letters were come across.”
This is not a new concept. Nearly two centuries ago, the American grammarian Goold Brown wrote about passive forms of intransitive verbs in his book The Institutes of English Grammar (1823):
“An active-intransitive verb, followed by a preposition and its object, will sometimes admit of being put into the passive form.” The object of the preposition becomes the subject, he wrote, and the preposition is “retained with the verb, as an adverb.”
His example: “They laughed at him” (active) becomes “He was laughed at” (passive).
As we said on our blog in 2014, a verb can be both transitive and intransitive. In fact, the phrasal verb “break in” can be both. Sometimes it’s transitive and requires an object; sometimes it’s intransitive and doesn’t.
For example, “break in” is transitive when it means to tame or train something like a horse. A direct object is required, as in “He broke in the colt.” In the passive, this becomes “The colt was broken in.”
But “break in” is intransitive when it means to forcibly intrude or to interrupt, as in “When the conversation got heated, Suzanne broke in.” No object is required.
If we add a prepositional phrase—“When things got heated, Suzanne broke in + to the conversation”—then we can make a passive sentence, though an awkward one: “When things got heated, the conversation was broken in + to.”
We’ll leave it to the reader to mentally rejoin “into.”
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