Paragraph One Children who are older by a wider gap tend to teach their younger siblings social and manual skills, almost like a third parent, while rivalry is usually greatest when the age difference is small. It is especially so when siblings are under four—they are easily displeased when gratification of their needs is postponed. 36. The role that age difference p___________in sibling rivalry.
【正确答案】：plays
【题目解析】：原文讲的是在年龄差距大的孩子中，大孩子就像父母一样教弟弟妹妹们社会技能和劳动技能；而年龄差距小的孩子们，尤其是四岁以下的，就会经常较劲。所以我们总结为年龄差在兄弟姐妹争吵中的作用，因此填plays。
