Does a quote have to be a full sentence?

Does a quote have to be a full sentence?

When a quotation is placed at the end of a sentence, but the quoted material is only part of a larger sentence, authorities differ on the use of ellipsis points. When using MLA-style parenthetical references, the sentence-terminating period is placed outside the parenthetical reference.

How long of a quote is too long?

There are no official limits to quotation length, though any quotations that are more than four lines should be formatted as a separate bl...