题目：

However, as people get older, friendships become more important than family relationships when it comes to ______ (predict) health and happiness.

when it comes to = as for; speaking about

这里的 to 是介词，后面要接名词或者动名词

• Bill is not good at maths and English, but when it comes to physics, he is the best one in his class.
• He is computer expert, but when it comes to cooking, he acts like an idiot.
• When it comes to selling services, Jerry is the best guy in his company.
• When it comes to teaching kids, you really need to be patient.

所以呢，前面的语法填空题正确的答案应该是：

However, as people get older, friendships become more important than family relationships when it comes to predicting health and happiness.