The old couple have been married for 40 years and never once _______ with each other.
A、theyhadquarreledC
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。
Youngerchildrenarecurious________howthingswork，andmanyofthemwanttotakeaparteverythingwithintheirreach.
_______ is a fact that English is being accepted as an international language.
The volunteers would rather go by train than ________.
______ofasentencedependsonthecontextinwhichthesentenceisuttered.
It is not decided ________ the conference will be held.
