单选题 The secretary is very diligent; ______ she can't get admission of the boss.
A. however B. therefore C. so D. although

【正确答案】 A

【答案解析】[解析] 本题考查连词。However意为“然而”，表示转折关系；therefore意为“因此”，表示因果关系；so意为“因此”，表示因果关系；although意为“虽然”，表示让步。这里是转折关系，故选A。