。
She didn't read that book.
Literal
She [topic-は] that book [object-を] didn't-read.
A clean, minimal example of plain past negative: 読む → 読まない → 読まなかった. The plainness of the form fits a casual or third-person narrative register. Without further context, the sentence is purely informational — no overt regret or excuse, just a flat statement of non-occurrence. A useful baseline against which the more elaborate 読まずにおいた ('left unread') or 読まなくて済んだ ('got away without reading') can be measured.