I am afraid I just ran out of film.The book has been out of print for some timenow.
四级词汇讲解:
这两句中两个相似的表达run out of和be out of,都表示“用完了;没有……了”。
英语四级考点归纳：
应当注意的是，有些与out有关的表达与be out of形似，含义却大不一样。如:
※ Out of sight, out of mind.眼不见，心不烦。
※ We've got to be out of our minds.我们一定昏了头。
※ David has been out of collar since last autumn。戴维从去年秋天起就失业了。
※ Don't trust him-he's only out for your money.别相信他—他只是图你的钱。
From:https://www.zgghmh.com/CET-4/20003672.asp