State-of-Being verbs express the existence of a subject, usually in some location at some point of time. The sentence structure is incredibly simple, and only forms of the verb “to be” are used for State-of-Being verb sentences. (See chart above for forms of “to be.” Also included are words like “should have been, could have been, would be, could be, am being, is being, are being.”)
Ex. Mary is at the mall right now.
In the example sentence, is expresses that the subject Mary exists at the mall (where) at a certain time, right now (when).
This type of sentence has an incredibly simple structure:
Subject + verb (a form of “to be”) + a word or phrase that tells where +a word or phrase that tells when
There doesn’t have to be the words or phrases that tell where or when, but when there are, no matter where those words or phrases are located in the sentence, the structure boils down to a subject and one of the forms of the verb “to be.”
Ex. Last weekend, Sue and Leon should have been in Chicago at a marriage conference.
Last weekend tells us when; in Chicago tells us where; at a marriage conference also tells us where, but more specifically. Therefore, when examining the remaining words in the sentence, Sue and Leon answer who or what the sentence is about, so they are the subjects, and should have been is another form of the verb “to be.” Consequently, although this sentence has many more words, it still boils down to a subject and one of the forms of the verb “to be,” so it is State-of-Being.