分析这句话的语法成分

题目

分析这句话的语法成分
Scientists say they have strong evidence that a biological problem could explain why some babies die suddenly in their sleep.
that后面接的是什么成分,that和evidence是什么关系,

答案

这儿的that是从句的引导词,引导的是同位语从句,修饰前面的evidence,而evidence则是这个同位语从句的先行词.
同位语从句的作用是对前面的先行词进行补充说明.
名词后面可以跟同位语从句和定语从句,很多人会混淆.最简单的区别是,
1) 定语从句可应用that,which等引导,而同位语从句只能用that引导.
2) 在同位语从句中,that不做任何成分,只起引导从句的作用.而在定语从句中that / which不但引导从句,而且还要做一个成分(主语,宾语,表语等.)
如:This is the evidence (that/ which) they have found.(这是他们已经找到的证据.)
本句中,that/which引导定语从句,修饰前面的先行词evidence,同时在从句中做have found的宾语.(做宾语时,that/which 可以省略.)
而你的句子中,从句a biological problem could explain why some babies die suddenly in their sleep有完整的主语,谓语,宾语,不缺少任何成分,所以我们可以判断that这儿引导的是一个同位语从句.