如果語(yǔ)義需要，unless 后接否定句也是可能的。如：　　

Are you determined to go? 一Unless my parents don’t approve of it. 你決心要去嗎? ——除非我父母不同意。——摘自《張道真英語(yǔ)語(yǔ)法》第432節(jié)　　

Girls remain on the register of their previous schools, and take their chosen exams there, unless they do not wish to go back into school.——摘自“英國(guó)國(guó)家語(yǔ)料庫(kù)”（可以 www.hz123456.com/Article/201111/2705.html  查找到）