some groups of people just happen to be fatter than others.happen to be什么结构
问题描述：
some groups of people just happen to be fatter than others.happen to be什么结构
答
主语（some groups of people ）谓语（happen）宾语（ be fatter ）宾语补语（ others.happen to be）
答
动词短语，happen to do，理解成“碰巧做了件什么事儿”
答
某些人群比另外一些人要胖一些,这是纯属偶然
1.happen to 偶然,碰巧
happen to do sth.= do sth.by chance= do sth.by accident
sb.happen to do sth./ happen to be adj.
2.另外,happen to 也有发生之意思,
sth.happen to sb.某事发生在某人身上