单选题 The new agent has experience ______not expertise.

A、 (A) but
B、 (B) and
C、 (C) with
D、 (D) however

【正确答案】 A

【答案解析】But is a conjunction that indicates a contrast between items. Choice (B) links items equally. Choice (C) indicates association. Choice (D) indicates contrast but links clauses, not phrases.