像句子My dad's got a camera that takes photos unger water.先行词 a camera是单数,从句that takes photos unger water的谓语动词就用takes
再如：The boys who are from America like China.这里主句是The boys like China.定语从句who are from America 修饰先行词the boys.因为the boys 是复数,所以定语从句who are from America 的谓语动词用复数are
如果还不明白,你可以倒过来做：把 1）The boys like China 2）THe boys are from America 两句改成定语从句.那么答案就是The boys who are from America like China