n.下向通风；下降气流；倒风；下吸；回流；空气陷坑
No watermark on a non-verbal-visual part of the silicone rubber layer easily scratched, Downdraft, expose their monlchamus photographicsensitive resin layer. 无水印版上否图文局部的硅橡胶层便当被划伤，而露不入其下吸不朱的感陡树脂层。
