单选题 Although he was ill, ______ he went on working.
A. but B. yet C. and D. while

【正确答案】 B
【答案解析】[解析] 词语辨析
[解析] A和D尽管有转折的意思，但不能与though/although同时使用。至于C项，则明显不符合句意，予以排除。