The verb “to be” can be used in descriptive clauses or as an auxiliary verb to create certain grammatical structures, such as the continuous tenses and the passive voice. This can lead to confusion when a verb or verb form follows the verb “to be” – how do you recognise which structure is being used? Consider this example: “The museum is supposed to be _______ in the morning.” (open) Opening would form the continuous tense, open would be an adjective form, opened would form a passive sentence. Each of these could be arguably correct – so how do we know the difference?
Identifying different uses of “to be”
In some cases, it will be clear from the sentence which form should follow “to be” – particularly when the context suggests you are describing something, or a time indicates a tense use:
- What I liked most was that the film was interesting. (What I liked suggests we are describing an attribute)
- They were reading all night long. (all night long gives a time for a process verb)
Phrases surrounding the verb can also give a clear indication of how the verb is being used. Prepositional phrases are particularly important here as they indicate how the verb connects to other ideas in the sentence, suggesting its use. It’s not enough to simply look at the preposition, as they can have various uses, but here are some general examples that may help identify the correct verb form.
For with a duration indicates time, which can suggest a continuous tense, though for followed by a noun can also indicate purpose, which can suggest either a continuous tense or a passive statement (e.g. We were waiting for ten minutes. / We were waiting for a bus.). This is less likely to indicate a description – though in some cases it might suggest a particular viewpoint (It was pleasing for me.)
To can be used as a preposition to indicate that a describing word impacts a noun (e.g. She was interesting to me.), but to as part of an infinitive would suggest the purpose of a continuous tense or passive statement (e.g. She was dancing to feel happy. , The window was opened to let in fresh air.).
By could be followed by a noun to indicate the actor of a verb, suggesting a continuous or passive use (e.g. The dinner was cooked by his mum.). Similarly, it can demonstrate location (The couple were kissing by the oak tree.). When by indicates a time, the verb use may not be immediately clear – They were walking by lunchtime. They were soaking by dinner. They were hidden by dusk.
In the example above, They were walking by lunchtime. Is a continuous statement but They were soaking by dinner. is in the past simple (with soaking used as an adjective). How do we know this? Because to soak is a transitive verb (requiring an object) – as there is no object in the sentence, we can see it is being used in an adjective form, not a verb form. In other cases, phrasal verb particles or particular forms that follow a verb (such as infinitives or +ing forms) can indicate a particular verb use. Another way to decide if an adjective form is used instead of a verb form is to replace it with another adjective – if the sentence still works, then the adjective form is possible.
- They were happy by dinner.
This does not necessarily mean a verb form isn’t possible, however; They were dancing by dinner. could also work.
These ideas are all clues to unravel the correct form – but in many cases we could have a “to be” statement where the sentence alone does not indicate a definite, correct form for the verb. For example: “It is _____ in Paris. (rain)” The correct answer is easy and clear If we know a verb or an adjective is required – but otherwise different forms could correct. It is raining in Paris. / It is rainy in Paris. Generally, understanding the context of your sentence will make this easy to decide – but this indicates how, often, there are no simple rules to explain what a word form should be when following “to be”.
“To be” + verbs Exercise
I’ve developed a short exercise to practice some of the different forms that follow “to be”. If you find any of these difficult, the answers below give explanations to help explain how to identify the correct form. I’ve repeated each root word twice to demonstrate different uses.
- The cat was _____ milk. (drink)
- The door was _____ by the security guard. (open)
- We are _____ these exercises hard. (find)
- This artwork is _____ to look at. (please)
- The man was _____ on wine. (drink)
- The bar was _____ all night. (open)
- Many people are _____ in the lobby. (wait)
- The escaped prisoners were _____ by the police. (find)
- He was _____ to be invited to the party. (please)
- She was _____ on by the restaurant manager himself. (wait)
- The cat was drinking milk.
- The door was opened by the security guard. (by followed by an actor indicates a passive form)
- We are finding these exercises hard. (there are no prepositions to indicate a separate actor, so no suggestion that this is passive)
- This artwork is pleasing to look at. (the context suggests the sentence is descriptive, and the correct adjective form (artwork has an external impact, pleasing, rather than receiving the pleasure, pleased)
- The man was drunk on wine. (the prepositional phrase indicates what caused a particular state, making it descriptive)
- The bar was open all night. (the time period indicates a state; it could also be used with a process verb (was opening all night) but the context suggests the state is more likely)
- Many people are waiting in the lobby. (there is no simple alternative to the verb form here – waited is not used as a descriptive word, though would be possible as a simple phrasal verb with on, waited on)
- The escaped prisoners were found by the police. (the prepositional phrase describes an actor so we know this is passive)
- He was pleased to be invited to the party. (the context suggests a state, his condition, but in this case he receives the pleasure rather than gives it, as in 4)
- She was waited on by the restaurant manager himself. (on tells this is a phrasal verb, while the preposition by tells us as actor did this verb to the subject, requiring the passive form)