题目

While income worry is a rather common problem of the aged, loneliness is another problem that aged parents may face. Of all the reasons that explain their loneliness, a large geographical distance between parents and their children is the major one. This phenomenon（现象）is commonly known as “Empty Nest Syndrome”（空巢综合症）.In order to seek better chances outside their countries, many young people have gone abroad, leaving their parents behind with no clear idea of when they will return home. Their parents spend countless lonely days and nights, taking care of themselves, in青藏高原是我国夏季气温最低的地区，主要原因A、纬度低 B、海拔低 C、纬度高 D、海拔高