Analysis of information sources in references of the Wikipedia article "Copula (linguistics)" in English language version.
Frajzyngier (1986) argues that copulas may also develop from prepositions
Using E- prime was supposed to add clarity to the language.
With the intent of improving clarity, directness, and honesty, E-Prime simplifies the English language by omitting the verb 'to be, along with its conjugates (i.e. am, are, is, was, were, been, being.) 'Be,' which does not exist in all languages [...] promotes passive, ambiguous language that can confuse or mislead recipients who have sensitivity to subtle judgments or untruths.