先行词 怎么判断先行词是谁

先行词是被定语从句所修饰的对象。在定语从句中充当一定的部分。之所以称它为先行词，是因为修饰它的定语从句总是放在它之后，先行词总是出现在定语从句之前，而不同于普通形容词修饰名词时，形容词位于名词之前。

判断定语从句先行词

定语从句的先行词可以是词，也可以是短语，更可以是句子。我们判断定语从句的先行词到底是谁，不能简单的去看定语从句关系词前的名词是谁，而是要更多地去看定语从句的语义，通过语义判断关系词应该指代的是谁，进而判断出先行词具体的内容。

（1）Behaviorists, in contrast, say that differences in scores are due to the fact that blacks are often deprived of many of the educational and other environmental advantages that whites enjoy.相反，行为主义者认为，成绩的差异是由于黑人往往被剥夺了白人在教育及其它环境方面所享有的许多有利条件。（在这个句子中最后一个that引导定语从句修饰advantages，advantage就是先行词）

（2）He likes climbing hills, which is a good exercise.他爱爬山，爬山是一种好的锻炼方式。（这个句子中which定语从句显然修饰的是climbing hills这个动名词短语，所以climbing hills是先行词。）

（3）This trend began during the Second World War，when several governments came to the conclusion that the specific demands that a government wants to make of its scientific establishment cannot generally be foreseen in detail.这种趋势始于第二次世界大战期间，当时一些国家的政府得出结论：政府向科研机构提出的要求通常是无法详尽预见的。（在这个句子当中，when引导定语从句修饰the Second World War名词短语，所以此名词短语是先行词。）

（4）He is quite lazy, which is known to all his neighbors.他很懒，邻居们都知道。（这个句子which修饰的对象只能是he is quite lazy整个句子，所以句子是先行词。）

（5）The food supply will not increase nearly enough to match this, which means that we are heading into a crisis in the matter of producing and marketing food.食品供应不会增加来满足这个要求,这意味着我们在生产和销售食品上面临危机。（这个句子中which引导定语从句修饰前面The food supply will not increase nearly enough to match this整句话。所以先行词是这整句话。）