he has been blind since birth, Joseph Chadbourne never feels different from his class-mates at school.
A. Since
B. Once
C. Unless
D. While
网友回答
A. Since
B. Once
C. Unless
(答案→)D. While
解析：考察连词辨析。A既然；自从；B一旦；C除非，如果…不…；D尽管；当…时；然而；句意：尽管出生时就看不见了，但是Joseph Chadbourne从未感觉到自己与学校的同学有什么不同。根据句意说明D正确。考生要特别注意连词的一词多义现象。