Be

From UNL Wiki

The verb "to be" may be used, in English:

"To be" as an intransitive verb (=UW): To exist in actuality; have life or reality: I think, therefore I am.; To occupy a specified position: The food is on the table.; To remain in a certain state or situation undisturbed, untouched, or unmolested: Let the children be.; To take place; occur: The test was yesterday.; To go or come: Have you ever been to Italy? Have you been home recently.
"To be" as a linking verb (= relation): To equal in identity: "To be a Christian was to be a Roman" (James Bryce).; To have a specified significance: A is excellent, C is passing. Let n be the unknown quantity.; To belong to a specified class or group: The human being is a primate.; To have or show a specified quality or characteristic: She is witty. All humans are mortal.; To seem to consist or be made of: The yard is all snow. He is all bluff and no bite.
"To be" as an auxiliary verb (= attribute): Used with the past participle of a transitive verb to form the passive voice: The mayoral election is held annually.; Used with the present participle of a verb to express a continuing action: We are working to improve housing conditions.; Used with the infinitive of a verb to express intention, ibs obligation, or future action: She was to call before she left. You are to make the necessary changes.; Archaic Used with the past participle of certain intransitive verbs to form the perfect tense: "Where be those roses gone which sweetened so our eyes?" (Philip Sidney).

The intransitive verb, but not the linking verb, may be replaced by an equivalent verb without changes in the meaning or in the structure: The food is on the table = The food is placed on the table; The test was yesterday = The test took place yesterday; Have you ever been to Italy? = Have you ever gone to Italy?; A is excellent = ?A means/is equal to excellent (= different meaning); The human being is a primate = ?The human being belongs to the class of primates (=structural change)