《英汉医学词典》source film distance 焦点-底片距离 source-film distance: 焦点底片距离; 射线源source-to-film distance: 放射源底片间距离source-to-film distance(sfd): 焦距(射线源到胶片距离)source distance: 震源矩focus source distance: 焦源距下载手机词典可随时随地查词查翻译