The last river ______ they crossed is two miles wide.为什么用 that 不能用 which
问题描述：
The last river ______ they crossed is two miles wide.
为什么用 that 不能用 which
答
当先行词被序数词或the very, the only, the last修饰时，要用that，不用which，作宾语时可以省去。
答
因为当先行词用last 修饰时, 指物的定语从句的关系代词只能用that ,而不能用which .
答
that
当先行词被序数词或被表次序的last 修饰时,指物一般用that,不用which
答
只能用that
当先行词中含有last, only等，定语从句的引导词只能用that，不能用which