参考答案

正确答案：D
解析：本题仍为细节题。题目问：over the hill指的是什么?由第一段关键句“For example, such commonly used phrases as 'over the hill'...denote old age as a period of impotency and incompetency (例如，这些惯用语‘over the hill’表示性无能和无能力的老年期)”可知，impotency and incompetency总的意思是lacking the ability，故选项D为正确答案。注意：over the hill本意是“上年岁的，走下坡路的”。