involutory collineation对合: convolution; folding; involu ...直射: collineation; perpendicular incidence; projectivity; shoot at right angles对合: convolution; folding; involution奇直射: singular collineation直射；共线: collineation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:对合直射，即可在微信中查询翻译
