The old couple have been married for 40 years and never once _______ with each other.
正确答案： C
本题解析：
本题考查的是倒装结构的用法。第二分句中因有否定副词 never 提前，故应用倒装结构;第一分句中的 have been married 已限定了时态，据此可排除 D 项。
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