The old couple have been married for 40 years and never once _______ with each other.
C
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havebeenmarried已限定了时态，据此可排除D项。
We ________ go out to restaurants, but mostly we eat at home.
Childrenhaveanatural________abouttheworldaroundthem.