Sindarin 

na

be

: The verb ”to be” is poorly attested. Apparently the root is na-. The imperative is attested as no, and nad (used = ”thing”) may be seen as an original gerund *”a being”. It seems that the copula ”is, are” (and ”was, were”?) can be omitted altogether, as in the ”Noldorin” sentence lheben teil brann i annon ”five feet high [is] the door” (AI:92), in Sindarin perhaps *leben tail brand i annon.