advance-diameter ratio近距: low coverage直径: diameter; diam比: 2螺距直径比: pitch diameter ratio; pitch ratio; pitch-diameter ratio标称螺距直径比: nominal pitch ratio下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:近距直径比，即可在微信中查询翻译
